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An Introduction to Chemical Science by R.P. Williams

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combined with O, it is, next to the latter, the most abundant of
elements. Silicates of Al, Fe, Ca, K, Na, and Mg are most common,
and these metals, in the order given, rank next in abundance.

291. Soils.--Beds of sand, clay, etc., are disintegrated rock.
Sand is chiefly SiO2; clay is decomposed feldspar, slatestone,
etc. Soils are composed of these with an added portion of
carbonaceous matter from decaying vegetation, which imparts a
dark color. The reddish brown hue so often observed in soils and
rocks results from ferric salts.

292. Minerals, of which nearly 1000 varieties are now known, may
be simple substances, as graphite and sulphur, or compounds, as
galena and gypsum. Only seven systems of crystallizations are
known, but these are so modified as to give hundreds of forms of
crystals. See Physics. A given chemical substance usually occurs
in one system only, but we saw in the case of S that this was not
always true.

Crystals of some substances deliquesce, or take water from the
air, and thus dissolve themselves. Some compounds cannot exist in
the crystalline form without a certain percentage of water. This
is called "water of crystallization"; if it passes into the air
by evaporation, the crystal crumbles to a powder- and is then
said to effloresce.

293. The Earth's Interior.--We are ignorant of the chemistry of
the earth's interior. The deepest boring is but little more than
a mile, and volcanic ejections probably come from but a very few
miles below the surface. The specific gravity of the interior is
known to be more than twice that of the surface rock. From this
it has been imagined that towards the center heavy metals like Fe
and Au predominate; but this is by no means certain, since the
greater pressure at the interior would cause the specific gravity
of any substance to increase.

294. Percentage of Elements.--Compute the percentage of O in the
following rocks, which compose a large proportion of the earth's
crust: SiO2, Al2SiO4, CaCO3. Find the percentage of O in pure
water. In air. Taking cellulose, C16H30O15, as the basis, find
the percentage of O in vegetation.

An estimate, based on Bunsen's analysis of rocks, of the chief
elements in the earth's crust, is as follows:--

O, 46 per cent Ca, 3 per cent
Si, 30 per cent Na, 2 per cent
Al, 8 per cent K, 2 per cent
Fe, 6 per cent Mg, 1 per cent

More than half the elements are known to exist in sea-water, and
the rest are thought to be there, though dissolved in such small
quantity as to elude detection. What four are found in the
atmosphere?CHAPTER LIV.

ORGANIC CHEMISTRY.

295. General Considerations.--Inorganic chemistry is the
chemistry of minerals, or unorganized bodies. Organic chemistry
was formerly defined as the chemistry of the compounds found in
plants and animals; but of late it has taken a much wider range,
and is now defined as the chemistry of the C compounds, since C
is the nucleus around which other elements centre, and with which
they combine to form the organic substances. New organic
compounds are constantly being discovered and synthesized, so
that nearly 100,000 are now known. The molecule of organic matter
is often very complex, sometimes containing hundreds of atoms.

In organic as in inorganic chemistry, atoms are bound together by
chemical affinity, though it was formerly supposed that an
additional or vital force was instrumental in forming organic
compounds. For this reason none of these substances, it was
thought, could be built up in the laboratory, although many had
been analyzed. In 1828 the first organic compound, urea, was
artificially prepared, and since then thousands have been
synthesized. They are not necessarily manufactured from organic
products, but can be made from mineral matter.

296. Molecular Differences.--Molecules may differ in three ways:
(1) In the kind of atoms they contain. Compare CO2 and CS2. (2)
In the number of atoms. Compare CO and CO2. (3) In the
arrangement of atoms, i.e. the molecular structure. Ethyl alcohol
and methyl ether have the same number of the same elements,
C2H6O, but their molecular structure is not the same, and hence
their properties differ.

Qualitative analysis shows what elements enter into a compound;
quantitative analysis shows the proportion of these elements;
structural analysis exhibits molecular structure, and is the
branch to which organic chemists are now giving particular
attention. `

A specialist often works for years to synthesize a series of
compounds in the laboratory.

297. Sources.--Some organic products are now made in a purer and
cheaper form than Nature herself prepares them. Alizarine, the
coloring principle of madder, was until lately obtained only from
the root of the madder plant; now it is almost wholly
manufactured from coal-tar, and the manufactured article serves
its purpose much better than the native product. Ten million
dollars' worth is annually made, and Holland, the home of the
plant, is giving up madder culture. Artificial naphthol-scarlet
is abolishing the culture of the cochineal insect. Indigo has
also been synthesized. Certain compounds have been predicted from
a theoretical molecular structure, then made, and afterwards
found to exist in plants. Others are made that have no known
natural existence. The source of a large number of artificial
organic products is coal-tar, from bituminous coal. Saccharine, a
compound with two hundred and eighty times the sweetening power
of sugar, is one of its latest products. Wood, bones, and various
fermentable liquids are other sources of organic compounds.

298. Marsh-Gas Series.--The chemistry of the hydro-carbons
depends on the valence of C, which, in most cases, is a tetrad.
Take successively 1, 2, and 3 C atoms, saturate with H, and note
the graphic symbols:--

H H H H H H
| | | | | |
H-C-H, or CH4. H-C-C-H, or? H-C-C-C-H, or ?
| | | | | |
H H H H H H

Write the graphic and common symbols for 4, 5, and 6 C atoms,
saturated with H. Notice that the H atoms are found by doubling
the C atoms and adding 2. Hence the general formula for this
series would be CnH2n+2. Write the common symbol for C and H with
ten atoms of C; twelve atoms; thirteen. This series is called the
marsh-gas series. The first member, CH4 methane, or marsh gas,
may be written CH3H, methyl hydride, CH3 being the methyl
radical. C2H6, ethane, the second one, is ethyl hydride, C2H5H.
Theoretically this series extends without limit; practically it
ends with C35H72.

In each successive compound of the following list, the C atoms
increase by unity. Give the symbols and names of the compounds,
and commit the latter to memory:--

Boiling-point.
1. CH4 methane, or CH3H, methyl hydride, gas.
2. C2H6 ethane, C2H5H, ethyl hydride, gas
3. C3H8 propane, C3H7H, propyl hydride, gas
4. ? butane, ? ? 1 degree
5. ? pentane ? ? 38 degrees
6. ? hexane, ? ? 70 degrees
7. ? heptane, ? ? 98 degrees
8. ? octane, ? ? 125 degrees
9. ? nonane, ? ? 148 degrees
10.? dekane, ? ? 171 degrees

Note a successive increase of the boiling-point of the compounds.
Crude petroleum contains these hydro-carbons up to 10.
Petroleumissues from the earth, and is separated into the
different oils by fractional distillation and subsequent
treatment with H2SO4, etc. Rhigoline is mostly 5 and 6; gasoline,
6 and 7; benzine, 7; naphtha, 7 and 8; kerosene, 9 and 10. Below
10 the compounds are solids. None of those named, however, are
pure compounds. Explosions of kerosene are caused by the presence
of the lighter hydro-carbons, as naphtha, etc. Notice that, in
going down the list, the proportion of C to H becomes much
greater, and the lower compounds are the heavy hydro-carbons. To
them belong vaseline, paraffine, asphaltum, etc.

299. Alcohols.--The following replacements will show how the
symbols for alcohols, ethers, etc., are derived from those of the
marsh-gas series. Notice that these symbols also exhibit the
molecular structure of the compound. In CH3H by replacing the
last H with the radical OH, we have CH3OH, methyl hydrate. By a
like replacement C2H5H becomes C2H5OH, ethyl hydrate. These
hydrates are alcohols, and are known as methyl alcohol, ethyl
alcohol, etc. The common variety is C2H5OH. How does this symbol
differ from that for water, HOH? Notice in the former the union
of a positive, and also of a negative, radical.

Complete the table below, making a series of alcohols, by
substitutions as above from the previous table.

1. CH3OH, methyl hydrate, or methyl alcohol.
2. C2H5OH, ethyl hydrate, or ethyl alcohol.
3. ? ? ?
4. ? ? ?
5. ? ? ?

Continue in like manner to 10.

The graphic symbol for CH3OH is---

H
|
H-C-OH;
|
H

for C2H5OH it is--

H H
| |
H-C-C-OH.
| |
H H

Write it for the next two.

300. Ethers.--Another interesting class of compounds are the
oxides of the marsh-gas series. In this series, O replaces H.
CH3H becomes (CH3)2O, and C2H5H becomes (C2H5)2O. Why is a double
radical taken? These oxides are ethers, common or sulphuric ether
being (C2H5)2O. Complete this table, by substituting O in place
of H, in the table on page 176.

1. (CH3)2O, methyl oxide, or methyl ether.
2. (C2H5)2O, ethyl oxide, or ethyl ether.
3. ? ? ?
4. ? ? ?
5, etc. ? ? ?

Graphically represented the first two are:--

H H H H H H
| | | | | |
(1) H-C-O-C-H. (2) H-C-C-O-C-C-H.
| | | | | |
H H H H H H

301. Substitutions.--A large number of other substitutions can be
made in each symbol, thus giving rise to as many different
compounds.

In CH4, by substituting 3 Cl for 3 H,--

H Cl
| |
H-C-H becomes H-C-CI, or CHCl3,the symbol for chloroform.
| |
H Cl

Replace successively one, two, and four atoms with Cl, and write
the common symbols. Make the same changes with Br. For each atom
of H in CH4 substitute the radical CH3, giving the graphic and
common formulae. Also substitute C2H5. Are these radicals
positive or negative? From the above series of formulae, of which
CH4 is the basis, are derived, in addition to the alcohols and
ethers, the natural oils, fatty acids, etc.

302. Olefines.--A second series of hydro-carbons is represented
by the general formula CnH2n. The first member of this series is
C2H4 or, graphically,--

H H
| |
C = C.
| |
H H

Compare it with that for C2H6, in the first series, noting
the apparent molecular structure of each.

H H
| |
C = C - C - H, or C3H6 is the second member.
| | |
H H H

Write formulae for the third and fourth members.

Write the common formulae for the first ten of this series. This
is the olefiant-gas series, and to it belong oxalic and tartaric
acids, glycerin, and a vast number of other compounds, many of
which are derived by replacements.

303. Other Series.--In addition to the two series of hydro-
carbons above given, CnH2n+2 and CnH2n, other series are known
with the general formulm CnH2n-2, CnH2n-4, CnH2n-6, CnH2n-8,
etc., as far as CnH2n-32, or C26H2O. Each of these has a large
number of representatives, as was found in the marsh-gas series.
Not far from two hundred direct compounds of C and H are known,
not to mention substitutions. The formula CnH2n-6 represents a
large and interesting group of compounds, called the benzine
series. This is the basis of the aniline dyes, and of many
perfumes and flavors.

Chapter LV.

ILLUMINATING GAS.

304. Source.--The three main elements in combustion are O, H, C.
Air supplies O, the supporter; C and H are usually united, as
hydro-carbons, in luminants and combustibles. H gives little
light in burning; C gives much. The fibers of plants contain
hydro-carbons, and by destructive distillation these are
separated, as gases, from wood and coal, and used for
illuminating purposes. Mineral coal is fossilized vegetable
matter; anthracite has had most of the volatile hydro-carbons
removed by distillation in the earth; bituminous and cannel coals
retain them. These latter coals are distilled, and furnish us
illuminating gas.

Experiment 129.--Put into a t.t. 20 g. of cannel coal in fine
pieces. Heat, and collect the gas over H2O. Test its
combustibility. Notice any impurities, such as tar, adhering to
the sides of the t.t., or of the receiver after combustion. Try
to ignite a piece of cannel coal by holding it in a Bunsen flame.
Is it the C which burns, or the hydrocarbons? Distil some wood
shavings in a small ignition-tube, and light the escaping gas.

305. Preparation and Purification.--To make illuminating gas,
fire-clay retorts filled with coal are heated to 1100 degrees or
more, over a fire of coke or coal. Tubes lead the distilled gas
into a horizontal pipe, called the hydraulic main, partly filled
with water, into which the ends of the gas-pipe dip. The gas then
passes through condensers consisting of several hundred feet of
vertical pipe, through high towers, called washers, in which a
fine spray Fig. 60. Gas Works.

A, furnace; C, retorts containing coal; T, gas-tubes leading to
B, the hydraulic main; D, condensers; O, washers, with a spray of
water, and sometimes coke; M, purifiers-ferric oxide or lime; G,
gas-holder. In C remain the coke and gas carbon. At B, D, E, and
O, coal tar, H2O, NH3, CO2, and SO2 are removed. At M are taken
out H2S and CO2.of water falls, into chambers with shelves
containing the purifiers CaO or hydrated Fe2O3, and finally into
a gas-holder, whence it is distributed. At the hydraulic main,
condensers, washers, and purifiers, certain impurities are
removed froth the gas. Coke is the solid C residue after
distillation. Gas-carbon, also a solid, is formed by the
separation of the heavier hydro-carbons at high temperature, and
is deposited on the sides of the retort.

Coal gas, as it leaves the retort, has many impurities. It is
accompanied with about 3 its weight of coal tar, 1/2 its weight
of H2O vapor, 1/50 NH3, 1/20 CO2, 1/20 to 1/50 H2S, 1/300 to
1/600 S in other forms. The tar is mostly taken out at the
hydraulic main, which also withdraws some H2O with other
impurities in solution. The condensers remove the rest of the
tar, and the H2O, except what is necessary to saturate the gas.
At the main, the condensers, and the washers, NH3 is abstracted,
CO2 and H2S are much reduced, and the other S compounds are
diminished. Lime purification removes CO2 and H2S, and, to some
extent, other S compounds. Iron purification removes H2S. Fe2O3 +
3 H2S = 2 FeS + S + 3 H2O.

The FeS is revivified by exposure to the air. 2 FeS + O3 = Fe2O3
+ 2S. It can then be used again. H2S, if not separated, burns
with the gas, forming H2S03, which oxidizes in the air to H2SO4;
hence the need of removing it. CO2 diminishes the illuminating
power.

306. Composition.--Even when freed from its impurities coal-gas
is a very complex mixture, the chief components being nearly as
follows:--

Percent Diluents, having little C, give
H 45) very little light. Notice the small
CH, 41) diluents. percentage of luminants, or light-
CO 5 ) giving compounds, also the proportion
C,HB 1.3) of C to H in them.
C,H6 1.2)luminants.
CZH4 2.5) Cannel coal contains more of
C02 2) impurities. the heavy bydro-carbons, CnH2n,
N, etc. 2) etc., than the ordinary bituminous
100 coal. Ten per cent of the coal should be
cannel; naphtha is, however, often employed to subserve the same
purpose, one ton of ordinary bituminous coal requiring four gallons
of oil.

In Boston, 7,000,000 cubic feet of gas have been burned in one
day, consuming 500 tons of coal; the average is not more than
half that quantity. Of the other products, coke is employed for
heating purposes, gas carbon is used to some extent in electrical
work, and coal-tar is the source of very many artificial products
that were formerly only of natural origin. NH3, is the main
source of ammonium salts, and S is made into H2SO4.

307. Natural Gas occurs near Pittsburg, Pa., and in many other
places, in immense quantities. It is not only employed to light
the streets and houses, but is used for fires and in iron and
glass manufactories. It is estimated that 600,000,000 cubic feet
are burned, saving 10,000 tons of coal daily in Pittsburg, Only
half a dozen factories now use coal. More than half the gas is
wasted through safety valves, on account of the great pressure on
the pipes as it issues from the earth.

These reservoirs of natural gas very frequently occur in
sandstone, usually in the vicinity of coal-beds, but sometimes
remote from them. In all cases the origin of the gas is thought
to be in the destructive distillation, extending through long
geological periods, of coal or of other vegetable or animal
matter in the earth's interior.

Natural gas varies in composition, and even in the same well,
from day to day; it consists chiefly of CH4, with some other
hydro-carbons.

CHAPTER LVI.

ALCOHOL.

308. Fermented Liquor.

Experiment 130.--Introduce 20 cc.of molasses into a flask of 200
cc, fill it with water to the neck, and put in half a cake of
yeast. Fit to this a d.t., and pass the end of it into a t.t.
holding a clear solution of lime water. Leave in a warm place for
two or three days. Then look for a turbidity in the lime water,
and account for it. See whether the liquid in the flask is sweet.
The sugar should be changed to alcohol and CO2. This is fermented
liquor; it contains a small percentage of alcohol.

309. Distilled Liquor. Experiment 131.--Attach the flask used in
the last experiment to the apparatus for distilling water (Fig.
32), and distil not more than one-fifth of the liquid, leaving
the rest in the flask. The greater part of the alcohol will pass
over. To obtain it all, at least half of the liquid must be
distilled; what passes over towards the last is mostly water.
Taste and smell the distillate. Put some into an e.d. and touch a
lighted match to it. If it does not burn, redistil half of the
distillate and try to ignite the product. Try the combustibility
of commercial alcohol; of Jamaica ginger, or of any other liquid
known to contain alcohol.

310. Effect on the System.

Experiment 132.--Put a little of the white of egg into an e.d. or
a beaker; cover it with strong alcohol and note the effect.
Strong alcohol has the same coagulating action on the brain and
on the tissues generally, when taken into the system, absorbing
water from them, hardening them, and contracting them in bulk.

311. Affinity for Water.

Experiment 133.--To show the contraction in mixing alcohol and
water, measure exactly 5cc.of alcohol and 5cc.of water. Pour them
together, and presently measure the mixture. The volume is
diminished. A strip of parchment soaked in water till it is limp,
then dipped into strong alcohol, becomes again stiff, owing to
the attraction of alcohol for water.

312. Purity.--The most important alcohols are methyl alcohol and
ethyl alcohol. The former, wood spirit, is obtained in an impure
state by distilling wood; it is used to dissolve resins, fats,
oils, etc., and to make aniline. It is poisonous, as are the
others.

Ethyl alcohol, spirit of wine, is the commercial article. It is
prepared by fermenting glucose, and distilling the product. It
boils at 78 degrees, vaporizing 22 degrees lower than water, from
which it can be separated by fractional distillation. By
successive distillations of alcohol ninety-four per cent can be
obtained, which is the best commercial article, though most
grades fall far below this. Five per cent more can be removed by
distilling with CaO, which has a strong affinity for water. The
last one per cent is removed by BaO. One hundred per cent
constitutes absolute alcohol, which is a deadly poison. Diluted,
it increases the circulation, stimulates the system, hardens the
tissues by withdrawing water, and is the intoxicating principle
in all liquors.--It is very inflammable, giving little light, and
much heat, and readily evaporates.

Beer has usually three to six per cent of alcohol; wines, eight
to twenty per cent. The courts now regard all liquors having
three per cent, or less, of alcohol, as not intoxicating. In
Massachusetts it is one per cent.

CHAPTER LVII.

OILS, FATS, AND SOAPS.

313. Sources and Kinds of Oils and Fats.--Oils and fats are
insoluble in water; the former are liquid, the latter solid. Most
fats are obtained from animals, oils from both plants and
animals. Oils are classified as fixed and essential. Castor oil
is an example of the former and oil of cloves of the latter.
Fixed oils include drying and non-drying oils. They leave a stain
on paper, while essential, or volatile oils, leave no trace, but
evaporate readily. Essential oils dissolved in alcohol furnish
essences. They are obtained by distilling with water the leaves,
petals, etc., of plants. Drying oils, as linseed, absorb O from
the air, and thus solidify. Non-drying ones, as olive, do not
solidify, but develop acids and become rancid after some time.

Oils and fats are salts of fatty acids and the base glycerin. The
three most common of these salts are olein, found in olive oil,
palmitin, in palm oil and human fat, and stearin, in lard. The
first is liquid, the second semi-solid, the last solid. Most fats
are mixtures of these and other salts.

Olefin = Glyceryl) ( oleic)
oleate ) ( )
Pahnitin = Glyceryl)salts from (palmitic)acid and glyceryl hydrate.
palmitate) ( )
Stearin = Glyceryl) (stearic )
stearate)

314. Saponification consists in separating these salts
into their acids and the base glycerin; soap-making is the best
illustration. To effect this separation, a strong soluble base is
used, KOH for soft, and NaOH for hard soap. Study this reaction:

Glyceryl oleate ) (sodium ) (oleate )
Glyceryl palmitate) + (hydrate) = sodium (palmitate) + (glyceryl
Glyceryl stearate ) (stearate ) (hydrate

Soaps are thus salts of fatty acids and of K or Na.

315. Soap is soluble in soft water, but the sodium stearate
probably unites with water to form hydrogen sodium stearate and
NaOH. The grease which exudes from the skin, or appears in
fabrics to be washed, is attacked by this NaOH and removed,
together with the suspended dirt, and a new soap is formed and
dissolved in the water. Hard water contains salts of Ca and Mg,
and when soap is used with it the Na is at once replaced by these
metals, and insoluble Ca or Mg soaps are formed. Hence in hard
water soap will not cleanse till all the Ca and Mg compounds have
combined.

316. Glycerin, C3H5(OH)3, is a sweet, thick, colorless, unctuous
liquid, used in cosmetics, unguents, pomades, etc. It is prepared
in quantity by passing superheated steam over fats when under
pressure.

317. Dynamite.--Treated with HNO3 and H2SO4 glycerin forms the
very explosive and poisonous liquid nitro-glycerin. In this
process the C3H5(OH)3 becomes C3H5(NO3)3. C3H5(OH)3 + 3HNO3 =
C3H5(NO3)3+3 H2O. H2SO4 is used to absorb the H2O which is
formed. Nitro-glycerin, absorbed by gunpowder, diatomaceous
earth, sawdust, etc., forms dynamite. For obvious reasons the
pupil should not experiment with these substances.

318. Butter and Oleomargarine.--Milk contains minute particles of
fat, about 1/500 of an inch in diameter, which give it the
whitecolor. These particles are lighter than the containing
liquid, and rise to the top as cream. Churning unites the
particles more closely, and separates them from the buttermilk.
The flavor of butter is due to the presence of five or ten per
cent of butyric and other acids of the same series.

It was found that cows gave milk after they ceased to have food;
hence it was inferred that the milk was produced at the expense
of the cows' fat. Why could not butter be artificially made from
the same fat? It was but a step from fat to milk, as it was from
milk to butter. Oleomargarine, or butterine, was the result. Beef
fat, suet, is washed in water, ground to a pulp, and partially
melted and strained, the stearin is separated from the filtered
liquid and made into soap, and an oily liquid is left. This is
salted, colored with annotto, mixed with a certain portion of
milk, and churned. The product is scarcely distinguishable from
butter, and is chemically nearly identical with it, though less
likely to become rancid from the absence of certain fatty acids;
its cost is perhaps one-third as much as that of butter.

Chapter LVIII

CARBO-HYDRATES.

319. Carbon and Water.--Some very important organic compounds
have H and O, in the proper proportion to form water, united with
C. The three leading ones are sugar, C12H22O11 or C12(H2O)11,
starch, C6H10O6, or ?, and cellulose, C18H30O15 or ?. Note the
significance of the name carbo-hydrates as applied to them.

320. Sugars may be divided into two classes,--the sucroses,
C12H22O11, and the glucoses, C6H12O6. Sucrose, the principal
member of the first class, is obtained from the juice of the
maple, the palm, the beet and the sugarcane; in Europe largely
from the beet, in America from cane. Granulated sugar is that
which has been refined; brown sugar is the unrefined. From the
sap evaporated by boiling, brown sugar crystallizes, leaving
molasses, which contains glucose and other substances. Good
molasses has but a small percentage of glucose. To refine brown
sugar it is dissolved in water, a small quantity of blood is
added to remove certain vegetable substances, after which it is
filtered through animal charcoal, i.e. bone-black, a process
which takes out the coloring-matter. The water is then evaporated
in vacuum-pans, so as to boil at about 74 degrees and to prevent
conversion into grape sugar. By this process much glucose or
syrup is formed, which is separated from the crystalline sucrose
by rapidly revolving centrifugal machines. Great quantities of
sucrose are used for food by all civilized nations. A single
refinery in New York purifies 2,000,000 pounds per day.

321. Glucose, or invert sugar, the principal member of the second
class, consists of two distinct kinds of sugar, --dextrose and
levulose. These differ in certain properties, but have the same
symbol. Both are found in equal parts in ripe fruits, while
sucrose occurs in the unripe. Honey contains these three kinds of
sugar.

Sucrose, by the action of heat, weak acids, or ferments, may be
resolved into the other two varieties. C12H22O11 + H2O = C6H12O6
+ C6H12O6. No mode of reversing this process, or of transforming
glucose into sucrose is known. Glucose is easily made from starch
or from the cellulose in cotton rags, sawdust, etc. If boiled
with dilute H2SO4 starch takes up water and becomes glucose.
C6H10O5 + H2O = C6H12O6.

CaCO3 is added to precipitate the H2SO4, which remains unchanged.
State the reaction. The product is filtered and the filtrate is
evaporated. Much glucose is made from the starch of corn and
potatoes.

322. Starch is found in all plants, especially in grains, seeds,
and tubers. Green plants--those containing chlorophyll--
manufacture their own starch from CO2 and H2O. These chlorophyll
grains are the plant's chemical laboratories, and hundreds of
thousands of them exist in every leaf. CO2 and a very little H2O
enter the leaf from the air, H2O being also drawn up through the
root and stem from the earth. In some unknown way in the leaf,
light has the power of synthesizing these into starch and setting
free O, which is returned to the atmosphere.6 CO2 + 5 H2O =
C6H10O5 + 12 O. As no such change takes place in darkness, all
green plants must have light. Parasitic plants, which are usually
colorless, obtain starch ready-made from those on which they
feed.

323. Uses.--Glucose is used in the manufacture of alcohol and
cheap confectionery, and in adulterating sucrose. It is only two-
thirds as sweet as the latter. The seeds of all plants contain
starch for the germinating sprout to feed upon; but starch is
insoluble, and hence useless until it is converted into glucose.
This is effected by the action of warmth, moisture, and a ferment
in the seed. Glucose is soluble and is at first the plant's main
food.

Commercial starch is made in the United States chiefly from corn;
in Europe, from potatoes. Differences in the size of starch
granules enable microscopists to determine the plant to which
they belong.

324. Cellulose, or woody fiber, is the basis of all vegetable
cell walls. Cotton fiber represents almost pure cellulose. From
it are made paper and woven tissues. In paper manufacture, woody
fiber is made into a pulp, washed, bleached, filtered, hot-
pressed, and sometimes glazed. Parchment paper, vegetable
parchment, is made by dipping unglazed paper for half a minute
into cold dilute H2SO4, 1 part H2O, 2 1/2 parts H2SO4, and then
washing. The fiber, by chemical change, is thus toughened. The
cell walls of wood are impure cellulose; hence the inferior
quality of paper made from wood-pulp. Paper is now employed for a
large number of purposes for which wood has heretofore been used,
such as for barrels, pails, and other hollow ware, wheels,
etc.

325. Gun-cotton is made by treating cotton fiber with H2SO4
and HNO3, washing and drying. To all appearances no change has
taken place, but the substance has become an explosive compound.

326. Dextrin, a gummy substance used for the backs of postage
stamps, is a carbo-hydrate, as in fact are gums in general.
Dextrin is made by heating starch with H2SO4 at a lower
temperature than for dextrose.

327. Zylonite and Celluloid. -These two similar substances embody
the latest use of cellulose in manufactured articles. For
zylonite, linen paper is cut into strips two feet by one inch,
soaked ten minutes in a mixture of H2SO4 and HNO3, a process
called nitration, washed for several hours, then ground to a fine
pulp, and thoroughly dried. It is then similar to pyroxiline.
Aniline coloring-matter of any desired shade is added, after
which it is dissolved by soaking some hours in alcohol and
camphor, the liquid is evaporated, and the substance is kneaded
between steam-heated iron rollers, dried with hot air, and
finally subjected to great pressure, to harden it, and cut into
sheets. Zylonite is combustible at a low temperature, and when in
the pyroxiline stage, explosively so. Ivory, coral, amber, bone,
tortoise shell, malachite, etc., are so closely imitated that the
imitation can only be detected by analysis. Collars, combs,
canes, piano-keys, and jewelry, are manufactured from it, and it
can be made transparent enough for windows.

CHAPTER LIX

CHEMISTRY OF FERMENTATION.

328. Ferments.--A large number of chemical changes are brought
about through the direct agency of bodies called ferments; their
action is called fermentation. Ferments are sometimes lifeless
chemical products found in living bodies; but in other cases they
are humble plants.

329. Yeast is one of the most common of living ferments, wild
yeast being a microscopic plant found on the ground near apple-
trees and grape-vines, and often in the air. The cultivated
variety is sold by grocers. The temperature best suited to the
rapid multiplication of the germs forming the ferment plant is 25
degrees to 35 degrees.

330. Alcoholic and Acetic Fermentation.--The changes which the
juice of the apple undergoes in forming cider and vinegar are a
good illustration of fermentation by a living plant. Apple-juice
contains sucrose. Yeast germs from the air, getting into this
unfermented liquor, cause it to "work." This process changes
sucrose to glucose, and glucose to alcohol and CO2, and is known
as alcoholic fermentation. The latter reaction, C6H12O6 = 2 C2H6O
+ 2 CO, is only partially correct, as other products are formed.
The juice has now become cider; the sugar alcohol. After a time,
if left exposed, another organism finds its way to the alcohol,
and transforms it into acetic acid, HC2H8O2, and H2O. This
process is called acetic fermentation. C2H6O + O2 = HC2H3O2 +
H2O. For this fermentation, a liquor should not have over ten per
cent of alcohol. Mother of vinegar consists of the germs that
caused the fermentation. Still a third species of ferment may
cause another action, changing acetic acid to H2O and CO2. The
vinegar then tastes flat. HC2H3O2 + 4 O = 2H2O + 2 CO2.

Some mineral acids, as H2SO4 and HCl, and some organic acids, are
regarded as lifeless ferments. To this class are thought to
belong the diastase of malt and the pepsin of the stomach. This
variety of ferments exists in the seeds of all plants, and
changes starch to glucose.

331. Bread which is raised by yeast is fermented, the object
being to produce CO2, bubbles of which, with the alcohol, cause
the dough to rise and make the bread light.

Grapes and other fruits ferment and produce wines, etc., from
which distilled liquors are obtained.

332. Lactic Fermentation changes the sugar of milk, lactose, to
lactic acid, i.e. sour milk. In canning fruit, any germs present
are killed by heating, and those from the air are excluded by
sealing the can. Milk has been kept sweet for years by boiling,
and tightly covering the receptacle with two or three folds of
cotton cloth.

333. Putrefaction is fermentation in which the products of decay
are ill-smelling. Saprophytes attack the dead matter, feed on it,
and cause it to putrefy. This action, as well as that of ordinary
fermentation, used to be attributed solely to oxygen. Germs bring
back organic matter to a more elementary state, and so have a
very important function. By some scientists, digestion is
regarded as a species of fermentation, probably due to the action
of lifeless ferments; e.g. sucrose cannot be taken into the
system, but is first fermented to glucose.

334. Most Infectious Diseases are now thought to be due to
parasites of various kinds, such as bacteria, microbes, etc.,
with which the victim often swarms, and which feed on his
tissues, multiplying with enormous rapidity. Such diseases are
small-pox, intermittent and yellow fevers, etc. Consumption, or
tuberculosis, is believed to be caused by a microbe which
destroys the lungs. In some diseases not less than fifteen
billions of the organisms are estimated to exist in a cubic inch.
These multiply so rapidly that from a single germ in forty-eight
hours may be produced nearly three hundred billions. These germs
do not spring into life spontaneously from inorganic matter, but
come from pre-existent similar forms. Parasites are not so rare
in the system even of a healthy person as is generally supposed.
They are found on our teeth and in many of the tissues of the
body.

Several infectious diseases are now warded off or rendered less
virulent by vaccination, the philosophy of which is that the
organisms are rendered less dangerous by domestication; several
crops, or generations, are grown in a prepared liquid, each less
injurious than its parent. Some of the more domesticated ones are
introduced into the system, and the person has only a modified
form of the disease, often scarcely any at all, and is for a more
or less limited time insured against further danger.

Dust particles and motes floating in the air are in part germs,
living or dead, often requiring only moisture and mild
temperature for resuscitation. Most of these are harmless.

Chapter LX.

CHEMISTRY OF LIFE.

335. Growth.--The chemistry of organic life is very complex, and
not well understood. A few of the principal points of distinction
between the two great classes of living organisms, plants and
animals, are all that can be noted here. Minerals grow by
accretion, i.e. by the external addition of molecules of the same
material as their interior. A crystal of quartz grows by the
addition of successive molecules of SiO2, arranged in a
symmetrical manner around its axis. The growth of crystals can be
seen by suspending a string in a saturated solution of CuSO4, or
of sugar. In plants and animals the growth is very much more
complex, but is from the interior, and is produced by the
multiplication of cells. To produce this cell-growth and
multiplication, food-materials must be furnished and assimilated.
In plants, sap serves to carry the food-materials to the parts
where they are needed. In the higher animals, vari- ous fluids,
the most important of which is the blood, serve the same purpose.

336. Chemistry of Plants.--In ultimate analysis, plants consist
mainly of C, H, O, N, P, K. In proximate analysis, as it is
called, they are found to contain these elements combined to form
substances like starch, sugar, etc. Water is the leading compound
in both animals and plants. One of the most important differences
between animals and plants is, that all plants, except parasitic
ones, are capable of building up such compounds as starch from
mineral food-stuffs, while animals have not that power, but must
have the products of proximate analysis ready prepared, as it
were, by the plant. Hence plants thrive on minerals, whereas
animals feed on plants or on other animals. The power which
plants have of transforming mineral matter is largely due to
sunlight, the action of which in separating CO, was described.
The reaction in the synthesis of starch from CO2 and H2O in the
leaf, is thought to be as follows: 6 CO2 + 5 H2O = C6H10O5 + 12
O. C6H10O5 is taken into the tree as starch; 12 O is given back
to the air. All the constituents, except CO2 and a very small
quantity of H2O, are absorbed by the roots, from the soil, from
which they are soon withdrawn by vegetation. To renew the supply,
fertilizers or manures are applied to the soil. These must
contain compounds of N, P, and K. N is usually applied in the
form of ammonium compounds, e.g. (NH4)2SO4, (NH4)2CO3, and
NH4NO3. The reduction and application of Cas(PO4)2 for this
purpose was described. K is usually applied in the form of KCl
and K2SO4.

337. Food of Man.--In the higher animals the object is not so much
to increase the size as to supply the waste of the system. The
principal elements in man's body are C, H, O, N, S, P.

An illustration of the transformation of mineral foods by plants
before they can be used by animals is found in the Ca3(PO4)2 of
bones. This is rendered soluble; plants absorb and transform it;
animals eat the plants and obtain the phosphates. Thus man is
said to "eat his own bones." The food of mankind may be divided
into four classes (1) proteids, which contain C, H, O, N, and
often S and P; (2) fats, and (3) amyloids, both of which contain
C, H, O; (4) minerals. Examples of the first class are the gluten
of flour, the albumen of the white of egg, and the casein of
cheese. To the second class belong fats and oils; to the third,
starch, sugar, and gums; to the fourth, H2O, NaCl and other
salts. Since only proteids contain all the requisite elements,
they are essential to human food, and are the only absolutely
essential ones, except minerals; but since they do not contain
all the elements in the proportion needed by the system, a mixed
diet is indispensable. Milk, better than any other single food,
supplies the needs of the system. The digestion and assimilation
of these food-stuffs and the composition of the various tissues
is too complicated to be taken up here; for their discussion the
reader is referred to works on physiological chemistry.

338. Conservation.--Plants, in growing, decompose CO2, and
thereby store up energy, the energy derived from the light and
heat of the sun. When they decay, or are burned, or are eaten by
animals, exactly the same amount of energy is liberated, or
changed from potential to kinetic, and the same amount of CO2 is
restored to the air. The tree that took a hundred years to
complete its growth may be burned in an hour, or be many years in
decaying; but in either case it gives back to its mother Nature,
all the matter and energy that it originally borrowed. The ash
from burning plants represents the earthy matter, or salts, which
the plant assimilated during its growth; the rest is volatile. In
the growth and destruction of plants or of animals, both energy
and matter have undergone transformation. Animals, in feeding on
plants, transform the energy of sunlight into the energy of
vitality. Thus "we are children of the sun."

CHAPTER LXI.

THEORIES.

339. The La Place Theory.--This theory supposes that at one time
the earth and the other planets, together with the sun,
constituted a single mass of vapor, extending billions of miles
in space; that it rotated around its center; that it gradually
shrank in volume by the transformation of potential into kinetic
energy; that portions of its outer rim were thrown off, and
finally condensed into planets; that our sun is only the
remainder of that central mass which still rotates and carries
the planets around with it; that the earth is a cooling globe;
that the other planets are going through the same phases as the
earth; and finally that the sun itself is destined like them to
become a cold body.

340. A Cooling Earth.--The sun's temperature is variously
estimated at many thousands, or even millions oŁ degrees. Many
metals which exist on the earth as solids -e.g. iron- are gases
in the dense atmosphere of the sun. Thus the earth, in its early
existence, must have been composed of gases only, which in after
ages condensed into liquids and solids. So intense was the heat
at that time, that substances probably existed as elements
instead of compounds, i.e. the temperature was above the point of
dissociation. We have seen that Al2O3, CaO, SiO2, etc., are
dissociated at the highest temperatures only. If the temperature
were above that of combination, compounds could not exist as
such, but matter would exist in its elemental state. On slowly
cooling, these elements would combine. It is, then, a fair
inference that such compounds as need the highest temperatures to
separate them, as silica, silicates, and some oxides, were formed
from their elements at a much earlier stage of the earth's
history than were those compounds that are more easily separable,
such as water, lead sulphide, etc., and that the most infusible
substances were solidified first.

341. Evolution.--As the earth slowly cooled, elements united to
form compounds, gases condensed to liquids, and these to solids.
At one time the entire surface of our planet may have been
liquid. When the cooling surface reached a point somewhat below
that of boiling water, the lowest forms of life appeared in the
ocean. This was many millions of years ago. Most scientists
believe that all vegetable and animal life has developed from the
lowest forms of life. There is also a theory that all chemical
elements are derivatives of hydrogen, or of some other element,
and that all the so-called elements are really compounds, which a
sufficiently high temperature would dissociate. As evidence of
this, it is said that less than half as many elements have been
discovered in the sun as in the earth, and that comets and
nebula, which are less developed forms of matter than the sun,
have a few simple substances only.

It is easy to fancy that all living bodies, both animal and
vegetable, are only natural growths from the lowest forms of
life; that these lowest forms are a development, with new
manifestations of energy, from inorganic matter; that compounds
are derived from elements; and that the last are derivatives of
some one element; but it must be borne in mind that this is only
a theory.

342. New Theory of Chemistry. We have seen that heat lies at the
basis of chemical as well as of physical changes. By the loss of
heat, or perhaps by the change of potential into kinetic energy,
in a nebulous parent mass, planets were formed, capable of
supporting living organisms. Heat changes solids to liquids, and
liquids to gases; it resolves compounds, or it aids chemical
union. In every chemical combination heat is developed; in every
case of dissociation heat is absorbed. Properly written, every
equation should be: a + b = c + heat; e.g. 2 H + 0 = H2O + heat;
or, c - a = b - heat; e.g. H2O - 2 H = 0 - heat. Another
illustration is the combination of C and O, and the dissociation
of CO2, as given on page 82. C + O2 = CO2 + energy. CO2 - O2 = C
- energy. In fact, there are indications that the present theory
of atoms and molecules of matter, as the foundation of chemistry,
will at no distant day give place to a theory of chemistry based
on the forms of energy, of which heat is a manifestation.

Chapter, LXII.

GAS VOLUMES AND WEIGHTS.

343. Oxygen.

Experiment 134.--Weigh accurately, using delicate balances, 5 g.
KClO3, and mix with the crystals 1 or 2 g. of pure powdered MnO2.
Put the mixture into a t.t. with a tight-fitting cork and
delivery-tube, and invert over the water-pan, to collect the gas,
a flask of at least one and a half liters' capacity, filled with
water. Apply heat, and, without rejecting any of the gas, collect
it as long as any will separate.

Then press the flask down into the water till the level in the
flask is the same as that outside, and remove the flask, leaving
in the bottom all the water that is not displaced. Weigh the
flask with the water it contains; then completely fill it with
water and weigh again.

Subtract the first weight from the second, and the result will
evidently be the weight of water that occupies the same volume as
the O collected. This weight, if expressed in grams, represents
approximately the number of cubic centimeters of water,--since 1
cc. of water weighs lg,--or the number of cubic centimeters of O.

At the time the experiment is performed the temperature should be
noted with a centigrade thermometer, and the atmospheric pressure
with a barometer graduated to millimeters.

Suppose that we have obtained 1450 cc. of O, that the temperature
is 27 degrees, and the pressure 758 mm.; we wish to find the
volume and the weight of the gas at 0 degrees and 760 mm.

According to the law of Charles--the volume of a given quantity
of gas at constant pressure varies directly as the absolute
temperature. To reduce from the centigrade to the absolute scale,
we have only to add 273 degrees. Adding the observed temperature,
we have 273 degrees + 27 degrees = 300 degrees. Applying the
above law to O obtained at 300 degrees A, we have the proportion
below. Since the volume of O at 273 degrees will be less than it
will at 300 degrees, the fourth term, or answer will be less than
the third, and the second term must be less than the first. 300 :
273 :: 1450 : x. This would give the result dependent upon
temperature alone.

By the law of Mariotte - Physics, - the volume of a given
quantity of gas at a constant temperature varies inversely as the
pressure. Applying this law to the O obtained at 758mm, we have
the following proportion. The volume at 760mm will be less than
at 758mm; or the fourth term will be less than the third; hence
the second must be less than the first. 760: 758:: 1450: x. This
would give the result dependent on pressure alone.

Combining the two proportions in one:--

300: 273 ):: 1450: x = 1316cc.
760: 758 )

1316cc=1.316 liters. It remains to find the weight of this gas. A liter of
H weighs 0.0896g. The vapor density of O is 16. Hence 1.316 liters of O
will weigh 1.316 X 16 X 0.0896 =1.89g.

(KClO3 = KCl + O3)
From the equation (122.5 48) we make a proportion,
( 5 x)

122.5: 5:: 48: x = 1.95, and obtain, as the weight of O contained in
5g of KClO3, 1.95g. The weight we actually,obtained was 1.89g. This
leaves an error of 0.06g, or a little over 4 per cent of error (0.06 / 1.95
= 0.03 +). The percentage of error, in performing this experiment,
should fall within 10.

Some of the liabilities to error are as follows:--

1. Impure MnO2, which sometimes contains C. CO2 is soluble m H2O.

2. Solubility of O in water.

3. Escape of gas by leakage.

4. Moisture taken up by the gas.

5. Difference between the temperature of the gas and that of the
air in the room.

6. Errors in weighing.

7. Want of accuracy in the weights and scales.

344. Hydrogen.

Experiment 135.--Weigh 5g, or less of sheet or granulated Zn, and
put it into a small flask provided with a thistle-tube and a
delivery-tube. Cover the Zn with water, and introduce through the
thistle-tube measured quantities of HCl, a few cubic centimeters
at a time. Collect the H over water in large flasks, observing
the same directions as in removing O. Weigh the water, compute
the volume of the gas, reduce it to the standard, and obtain the
weight, as before. Should any Zn or other solid substance be
left, pour off the water or filter it, weigh the dry residue, and
deduct its weight from that of the Zn originally taken. Suppose
the residue to weigh 0.5g. Make and solve the proportion from the
equation:-

Zn + 2HCl = ZnCl2 + 2H.
65 2.
4.5 x.

Compute the percentage of errcr, as in the case of O. If the
purity of the HCl be known, i.e. the weight of HCl gas in one
cubic centimeter of the liquid, a proportion can be made between
HCl and H, provided no free HCl is left in the flask. State any
liabilities to error in this experiment.

PROBLEMS.

(1) A gas occupies 2000cc.when the barometer stands
750mm. What volume will it fill at 760mm?

(2) At 750mm my volume of O is 4 1/2 liters. What will it be at
730mm?

(3) At 825mm?

(4) At 200mm?

(5) Compute the volume of a gas at 70 degrees, which at 30
degrees is 150cc.

(6) At 0 degrees I have 3000cc.of O. What volume will it occupy
at 100 degrees?

(7) I fill a flask holding 2 litres with H. The thermometer
indicates 26 degrees, the barometer 762mm. What is the volume of
the gas at 0 degrees and 760mm?

If the volumes of gases vary as above, it is evident that their
vapor densities must vary inversely. A liter of H at 0 degrees
weighs 0.0896. What will a liter of H weigh at 273 degrees? At
273 degrees the one liter has be- come two liters, one of which
weighs 0.0448 (= 0.0896 / 2). The vapor density of a gas is
inversely proportional to the temperature. Also, the vapor
density is directly proportional to the pressure, since a liter
of any gas under a pressure of one atmosphere is reduced to half
a liter under two atmospheres.

PROBLEMS.

(1) Find the weight of a liter of O at 0 degrees; then compute the
weight of a liter at 27 degrees.

(2) Find the weight of 500cc.of N2O at 60 degrees.

(3) Of 200 cc. of CO at -5 degrees.

(4) A given volume of O weighs 0.25g at a pressure of 750mm; find
the weight of a like volume of O at 758mm.

APPENDIX.

INDIVIDUAL APPARATUS.

Each pupil should be provided with the apparatus given below, but in
cases where great economy must be exercised different pupils may, by
working at different times, use the same set. The author has selected
apparatus specially adapted, as to exact dimensions, quality, and cheap-
ness, for performing in the best way the experiments herein described,
and sets or separate pieces of this, together with other apparatus and
chemicals, can be had of the L.E. Knott Apparatus Co., 14 Ashburton
Place, Boston, to which firm teachers are referred for catalogs.

4 wide-mouthed bottles (horse-radish size), with corks.
1 soda-bottle.
4 pieces window-glass (3 in. sq.).
2 pieces thick glass tubing (20 in. long, 4 in. outside diam.).
1 glass stirring-rod.
1 glass funnel (2 1/2 in. wide, 60 degrees).
2 pieces glass tubing (12 in. long; 5/8 in. diam.).
1 porcelain evaporating-dish (3 in. wide).
1 asbestus paper and 1 fine wire gauze (3 in. sq.).
1 iron (or tin) plate.
1 pair forceps.
1 triangular file and 1 round file.
1 copper wire (15 in. long).
6 test-tubes, and corks to fit.
1 wooden test-tube holder.
1 flask with cork (200cc).
1 Bunsen burner (or alcohol lamp).
1 iron ring-stand.
1 piece rubber tubing (18 in. long,
3/8 in. inside diam.).
4 reagent bottles (250cc), HCl, HNO3, H2SO4, NH4OH.
1 pneumatic trough.

Wherever in this work "Bunsen burner" or "lamp" is mentioned, if
gas is not to be had, an alcohol lamp may be substituted.

GENERAL APPARATUS.

The following list includes apparatus needed for occasional
use:--

Metric rules (20 or 30cm long).
Scales with metric weights (1-200 g).
Metric graduates (25 or 50cc).
Filter papers.
Metric graduates (500cc).
Reagent bottles (250 and 500cc).
Mouth blowpipes.
Platinum wire and foil.
Mortars and pestles.
Test-tube racks.
Thistle-tubes.
Filter-stands.
Beakers.
Glass tubing (3/16 in., 1/4 in., and 1 in. outside).
Rubber tubing (1/8 in., and 3/8 in. inside).
Hessian crucibles.
Porcelain crucibles.
Electrolytic apparatus, including 2 or more Bunsen cells.
Ignition-tubes.
Steel glass-cutters.
Wire-cutters.
Calcium chloride tubes.
Water baths.
Thermometers.
Barometers, etc.

APPENDIX.

CHEMICALS.

The following estimate is for twenty pupils: -
Alcohol 1 pt
Alum 1 oz
Ammonium chloride 1/2 lb
Ammonium hydrate 1 lb
Ammonium nitrate. 1/2 lb
Antimony (powdered metallic) 1/2 oz.
Arsenic (powdered metallic) 1/2 oz.
Arsenic trioxide..... 1 oz.
Barium chloride..... 1 oz.
Barium nitrate..... 1 oz.
Beeswax....... 1 oz.
Bleaching-powder.... 1/4 lb.
Bone-black...... 1/2 lb.
Bromine....... 1/4 lb.
Calcium chloride.... 1 lb.
Calcium fluoride (powdered) 1 lb.
Cannel coal 1 lb
Carbon disulphide 1/4 lb
Chlorhydric acid 6 lb
Cochineal 1 oz
Copper (filings) 2 lb.
Copper nitrate 1 oz
Copper oxide 1/4 lb.
Ether (sulphuric) 1/4 lb
Ferrous sulphide 1 lb.
Ferrous sulphate 1/4 lb
Indigo 1/4 lb
Iodine 1 oz
Iron (filings or turnings) 1 lb.
Lead (sheet) 4 lb
Lead acetate 1 oz
Lead nitrate 1/4 lb
Litmus 1/2 oz
Litmus paper 3 sheets
Magnesium ribbon.... 3 ft.
Manganese dioxide.... 2 lb.
Mercurous nitrate.... 1/2 oz.
Nitric acid 3 lb.
Oxalic acid 1/4 lb
Phosphorus 1/4 lb
Potassium (metallic) 1/8 oz
Potassium bromide 1/4 lb.
Potassium dichromate 1/4 lb.
Potassium chlorate 2 lb.
Potassium hydrate 1/4 lb.
Potassium iodide 2 oz
Potassium nitrate 1/4 llb
Silver nitrate 1 oz.
Sodium 1/8 oz.
Sodium carbonate 1/4 lb
Sodium hydrate 1 lb.
Sodium nitrate 1/2 lb
Sodium silicate..... 1/2lb
Turkey red cloth.... 1/2yd
Sodium sulphate..... 1/4lb
Turpentine(spirits). 1/4lb
Sodium sulphide..... 1/4lb
Zinc(granulated).... 2lb
Sodium thiosulphate. 1/4lb
Zinc foil........... 3ft
Sulphur............. 2lb
Sulphuric acid...... 12lb

Additional Material

These substances are best obtained of local dealers.

Calcium carbonate(marble)..... 1lb
Molasses...................... 1pt
Calcium oxide(unslaked lime).. 1lb
Sodium chloride(fine)......... 1lb
Charcoal...................... 1lb
Sodium chloride(coarse)....... 1lb
Sheet lead.................... 4lb
Sugar......................... 1/2lb

FOR EXAMINATION

Those in capitals are most important

Rocks and Minerals.
ARGILLITE,
ARESENIC,
ARSENOPYRITE,
Barite,
CALCITE,
CASSITERITE,
CHALCOPYRITE,
CHALK,
CINNABAR,
COPPER (native),
Corundum,
Dolomite,
EMERY,
FELDSPAR,
Flint,
GALENITE,
GRANITE,
GRAPHITE,
GYPSUM,
HEMATITE,
Hornblende,
Jasper,
LIMONITE,
MAGNESITE,
MAGNETITE,
MALACHITE,
Meerschaum,
MICA,
OBSIDIAN,
Orpiment,
PYRITE,
QUARTZ,
Realgar,
SAND,
SERPENTINE,
SIDERITE,
SPHALERITE,
Talc,
ZINCITE

Metals and Alloys.

Aluminium, Iron (cast),
Aluminium bronze. Pewter,
Bell metal, Solder,
Brass, Steel,
Bronze, Type metal,
Copper, Tin foil,
Galvanized iron, Tin (bright plate and terne plate),
German silver, Zinc (sheet).
Iron (wrought)

Additional Compounds, for Examination:

Copper acetate, Lead carbonate,
Copper arsenite, Red lead,
Copper nitrate, Magnesia alba,
Copper sulphate, Smalt,
Lead dioxide, Vermilion.
Lead protoxide,

TABLE OF SOLUTIONS.

Number of grams of solids to be dissolved in 500cc of water.

AgNO3......... 25 K2Al2(SO4)4...... 50
BaCl2......... 50 KBr.... 25
Ba(N0 3)2........ 30 K2Cr207........ 50
CaClz......... 60 KI.......... 25
Ca(OH)2...... saturated KOH....... 60
CaS04....... saturated NaICOS........ 50
CUC12 50 NaOH 60
Cu(N03)......... 50 NalSl03....... saturated
FeS04......... 50 NH,N03........ 50
HgC12......... 30 Pb(C2H302)2...... 50
HgN03..... 25 + 25 HN03 Pb(NOs)2....... . 50

Other solutions....saturated.

Indigo solution (sulphindigotic acid) is prepared by heating for
several hours over a water bath, a mixture of ten parts of H 2SO4
with one of indigo, and, after letting it stand twenty-four
hours, adding twenty parts of water and filtering.

TEXTBOOK ADVERTISEMENTS THAT APPEARED IN THE ORIGINAL EDITION

INTRODUCTION TO CHEMICAL SCIENCE

By R.P. WILLIAMS, Instructor in Chemistry in the English High
School, Boston. l2mo. Cloth. 216 pages. By mail, 90 cents; for
introduction, 80 cents.

This work is strictly, but easily, inductive. The pupil is
stimulated by query and suggestion to observe important
phenomena, and to draw correct conclusions. The experiments are
illustrative, the apparatus is simple and easily made. The
nomenclature, symbols, and writing of equations are made
prominent features. In descriptive and theoretical chemistry, the
arrangement of subjects is believed to be especially superior in
that it presents, not a mere aggregation of facts, but the
science of chemistry. Brevity aud concentration, induction,
clearness, accuracy, and a legitimate regard for interest, are
leading characteristics. The treatment is full enough for any
high school or academy.

Though the method is an advanced one, it has been so simplified
that pupils experience no difficulty, but rather an added
interest, in following it.

The author himself has successfully employed this method in
classes so large that the simplest and most practical plan has
been a necessity.

Thomas C. Van Nuys, Professor of Chemistry, Indiana University,
Bloomington, Ind.:

"I consider it an excellent work for students entering upon the
study of chemistry."

C.F. Adams, Teacher of Science, High School, Detroit, Mich.:

"I have carried two classes through Williams's Chemistry. The
book has surpassed my highest expectations. It gives greater
satisfaction with each succeeding class."

J.W. Simmons, County Superintendent of Schools, Owosso, Mich.:

"The proof of the merits of a textbook, is found in the crucible
of the class-room work. There are many chemistries, and good
ones; but, for our use, this leads them all. It is stated in
language plain, interesting and not misleading. A logical order
is followed, and the mind of the student is at work because of
the many suggestions offered. We use Williams's work, and the
results are all we could wish. There is plenty of chemistry in
the work for any of our high schools."

W.J. Martin, Professor of Chemistry, Davidson College, N.C.:

"One of the most admirable little text-books I have ever seen."

T.H. Norton, Projessor of Chemistry, Cincinnati University, O.:

"Its clearness, accuracy, and compact form render it
exceptionally well adapted for use in high and preparatory
schools. I shall warmly recommend it for use, whenever the effort
is made to provide satisfactory training in accordance with the
requirements for admission to the scientific courses of the
University."

CHEMICAL EXPERIMENTS

General and Analytical. By R.P. WILLIAMS, Instructor in
Chemistry, English High School, Boston. 8vo. Boards. xv + 212
pages. Fully illustrated. Mailing price, 60 cents; for
introduction, 50 cents.

This book is for the use of students in the chemical laboratory.
It contains more than one hundred sets of the choicest
illustrative experiments, about half of which belong to General
Chemistry, the rest to Metal and Acid Analysis.

Great care has been taken to describe accurately and minutely the
methods of performing experiments, and in directing pupils to
observe phenomena and to explain what is seen. The work is amply
illustrated and is replete with questions and suggestions. Blank
pages are inserted for pupils to make a record of their work, for
which careful directions are given, with a model, laboratory
rules, tables of solubilities, etc.

A new feature is the supplementary and original work, vhich is
given at the end of each set of experiments for such pupils as
complete the prescribed work ahead of others in the class, and a
list of terms to be looked up in some text-book. This gives an
elasticity to the book and fits it for use in schools where much
time is devoted to chemistry, as well as in the most elementary
classes in labortttory work.

Another original feature which it is believed will be heartily
welcomed by teachers is the method of treating Metal Analysis
successfully used by the author for several years.

Briefly, the aim of this book is to aid the pupil to do, to
observe, to explain, to record, aud thus to learn the essentials
of chemistry.

LABORATORY MANUAL OF GENERAL CHEMISTRY

By R.P. WILLIAMS, Instructor in Chemistry, English High School,
Boston. 12mo. Boards. xvi + 200 pages. by mail, 30 cents; for
introduction, 25 cents.

The book contains one hundred experiments in general chemistry
aNd qualitative analysis, blanks opposite each for pupils to to
take notes, laboratory rules, complete tables of symbols, with
chemical and common names, reagents, solutions, chemicals, and
apparatus, and the plan of a model laboratory.

AN ELEMENTARY CHEMISTRY

By GEORGE R. WHITE, Instructor in Chemistry at Phillips Academy,
Exeter. 12mo. Cloth. xxix + 272 pages. Mailing price, $1.10; for
introduction, $1.00.

This is an excellent text-book for High Schools and Academies,
and for elementary classes in Colleges. The strictly inductive
method here followed, together with the insertion of numerous
questions that must cause the student to do his own reasoning
from the observations, renders this book particularly useful.

T.H. Norton, Professor of Chemistry, University of Cincinnati,
Cincinnati, Ohio.:

"I am greatly pleased with the plan and its execution. It is an
admirable arrangement for our inductive course in chemistry and
should not fail to yield good results."

A STUDENTS' MANUAL OF A LABORATORY COURSE IN PHYSICAL
MEASUREMENTS

By Wallace C. Sabine, Assistant Professor of Physics, Harvard
University. 8vo. Cloth. ix + 126 pages. Mailing price, $1.35; for
introduction, $1.25.

This manual, which is intended for use in supplementing college
courses in physics, contains an outline of seventy experiments,
arranged with special regard to a systematic and progressive
development of the subject.

Le Roy C. Cooley, Professor of Physics, Vassar College:

"I have examined it and am ready to commend it."

J.F. Woodhull, Professor of Sciences, Teachers' College, New
York:

"I find Sabine's Laboratory Manual a thoroughly good thing."

HIGH SCHOOL LABORATORY MANUAL OF PHYSICS

By Dudley G. Hays, Charles D. Lowry, and Austin C. Rishel,
Teachers of Physics in the Chicago High Schools. 8vo. Cloth. iv +
154 pages. Mailing price, 60 cents; for introduction, 50 cents.

This manual has been written: First, to present a logically
arranged course of experimental work covering the ground of
Elementary Physics. Second, to provide sufficient laboratory work
to meet college entrance requirements.

The experiments are largely quantitative, but qualitative work is
introduced.

W.S. Jackman, Teacher of Science, Cook Co. Normal School,
Englewood, Ill.:

"It is a most excellent manual, and I believe it meets the needs
of high schools on this subject better than any other book I have
seen."

YOUNG'S LESSONS IN ASTRONOMY

Including Uranography. Revised Edition. By CHARLES A. YOUNG,
Professor of Astronomy in the College of New Jersey. 12mo. Cloth.
Illustrated. ix + 357 pages, exclusive of four double-page star
maps. By mail, $1.30; for introduction, $1.20.

The revised edition of this book has been prepared for schools
that desire a brief course free from mathematics. It is based
upon the author's Elements of Astronomy, but many changes of
arrangement have been made. In fact, everything has been
carefully worked over and re-written to adapt it to the special
requirements. Great pains has been taken not to sacrifice
accuracy and truth to brevity, and no less to bring everything
thoroughly down to date. The latest results of astronomical
investigation will be found here. The author has endeavored, too,
while discarding mathematics, to give the student a clear
understanding and a good grasp of the subject. As a body of
information and as a means of discipline, this book will be
found, it is believed, of notable value. The most important
change in the arrangement of the book has been in bringing the
Uranography, or constellation tracing, into the body of the text
and placing it near the beginning, a change in harmony with the
accepted principle that those whose minds are not mature succeed
best in the study of a new subject by beginning with what is
concrete and appeals to the senses, rather than with the abstract
principles. Brief notes on the legendary mythology of the
constellations have been added for the benefit of such pupils as
are not likely to become familiar with it in the study of
classical literature.

N.W. Rarrington, President of University of Washington, Seattle,
Wash., formerly chief of the U.S. Weather Bureau, Washington,
D.C.:

"I shall take pleasure in commending it to schools requiring an
astronomy of this grade. The whole series of Astronomies reflects
credit on their distinguished author and shows that he
appreciates the needs of the schools."

Clarence E. Kelly, Prin. of High School, Haverhill, Mass.:

"It seems to me the book is admirably adapted to its purpose, and
that it accomplishes the difficult task of presenting to the
student or reader not conversant with Algebra and Geometry, an
excellent selection of what may with profit be given him as an
introduction to the science of astronomy."

YOUNG'S ELEMENTS OF ASTRONOMY

With a Uranography. By CHARLES A. YOUNG, Professor of Astronomy
in the College of New Jersey. 12mo. Half leather. x + 472 pages,
and four star maps. Mailing price, $1.55: for introduction,
$1.40.

Uranography.

From Youpg's Elements of Astronomy. 12mo. Flexible covers. 42
pages. besides four star maps. By mail, 35 cents; for
introduction, 30 cents.

This volume is an independent work, and not an abridgment of the
author's General Astronomy. It is a text-book for advanced High
Schools, Seminaries, and Brief Courses in colleges generally. It
was prepared by one of the most distinguished astronomers of the
world, a most popular lecturer, and most successful teacher. It
had every presumption in its favor, and the event has more than
justified expectations. Special attention has been paid to making
all statements correct and accurate so far as they go.

In the text no mathematics higher than elementary algebra and
geometry is introduced; in the foot-notes and in the Appendix an
occasional trigonometric formula appears, for the benefit of the
very considerable number of High school students who understand
such expressions.

G.B. Merriman, formerly Prof. of Mathemutics and Astronomy,
Rutgers College, New Brunswick, N.J.:

"For a short course in elementary astronomy, it is by far the
best book I have ever examined."

Warren Mann, State Normal School, Potsdam, N. Y.:

"Accuracy in use of terms is a marked feature. I consider it the
best text-book on this subject."

H.N. Chute, High School, Ann Arbor, Mich.:

"It is just the book the scholars have been waiting for."

G.H. Howe, State Normal School, Warrensburg, MO.:

"It is indeed an admirable book, up to the times, clear, and
complete."

Jeremiah Slocum, South Division High School, C&ugo, Ill.:

"It is well adapted both as to scope and manner of treatment to
high-school work."

Ray G. Huling, Prin. of English High School, Cambridge, Mass.:

"It is delightfully fresh, full, and clear."

A.S. Roe, recently of High School, Worcester, Muss.:

"The book is extended enough to please the exacting teacher."

I.P. Bishop, State Normal School, Buffalo, N.Y.:

"The book seems to have all the essentials of a first-class text
for high school work; viz., conciseness, clearness, and the
results of recent research."

YOUNG'S GENERAL ASTRONOMY

A Text-book for Colleges and Technical Schools. By CHARLES A .
YOUNG, Professor of Astronomy in the College of New Jersey. 8vo.
viii + 551 pages. Half morocco. Illustrated with over 250 cuts
and and diagrams, and supplemented with the necessary tables.
Mailing price, $2.50; for introduction, $2.25.

In amount, the work has been adjusted as closely as possible to
the prevailing courses of study in our colleges. By omitting the
fine print, a briefer course may be arranged.

The eminence of Professor Young as an original investigator in
astronomy, a lecturer and writer on the subject, and an
instructor of college classes, and his scrupulous care in
preparing this volume, led the publishers to present the work
with the highest confidence; and this confidence has been fully
justified by the event. More than one hundred colleges adopted
the work within a year from its publication, and it is conceded
to be the best astronomical text-book of its grade to be found
anywhere.

Edw. C. Pickering, Prof. of Astronomy, Harvard University:

"I think this work the best of its kind, and admirably adapted to
its purpose."

S.P. Langley, Sec. Smithsonian Inst., Washington, D.C.:

"I know no better book (not to say as good a one) for its
purpose, on the subject."

AN INTRODUCTION TO SPHERICAL AND PRACTICAL ASTRONOMY

By DASCOM GREENE, Professor of Mathematics and Astronomy in the
Rensselaer Polytechnic Institute, Troy, N.Y. NW. Cloth.
Illustrated. viii + 158 pages. Mailing price, $1.60; for
introduction, $1.50.

The book is intended for class-room use and affords such a
preparation as the student needs before entering upon the study
of the larger and more elaborate works on this subject.

The appendix contains an elementary exposition of the method of
least squares.

Daniel Carhart, Act. Prof. Mathematics, Western Univ. of Pa.,
Allegheny, Pa.:

"Professor Greene has supplied that which is needed to make the
usual course in Astronomy in our colleges more practical."

Rodney G. Kimball, Polytechnic Institute, Brooklyn, N.Y.:

"The hasty examination which I have given it has left a very
favorable impression as to its merits as a judicious compound of
the practical work which it professes to cover."

SCHEINER'S ASTRONOMICAL SPECTROSCOPY

Department of Special Publication.--Revised Edition. Translated,
revised and enlarged by E.B. FROST, Professor of Astronomy in
Dartmouth College. 8vo. Half leather. Illustrated. xiii + 482
pages. Price by mail, $5.00; for introdoctiort, $4.75.

This work aims to explain the most practical and modern methods
of research, and to state our present knowledge of the
constitution, physical condition alld motions of the heavenly
bodies, as revealed by the spectroscope.

Edward S. Holden, Director of the Lick Observatory, Mt. Hamilton,
California:

"I congratulate you on the appearance of this very important
book; it is indispensable to all astronomers and students of
spectroscopy."

ELEMENTS OF PLANT ANATOMY

By EMILY L. GREGORY, Professor of Botany in Barnard College. 8vo.
Cloth. viii + 148 pages. Illustrated. Mailing price, $1.35; for
introduction, $1.25.

This book is designed as a text-book for students who have
already some knowledge of general botany. It consists of an
outline of the principal facts of plant anatomy, in a form
available not only for those who wish to specialize in botany but
for all who wish to know the leading facts about the inner
structure of plants. It affords a preparation for the study of
the more intricate and difficult questions of plant anatomy and
physiology, while it is especially adapted to the wants of
students, who need a practical knowledge of plant structure.

ELEMENTS OF STRUCTURAL AND SYSTEMATIC BOTANY

For High Schools and Elementary College Courses. By DOUGLAS H.
CAMPBELL, Professor of Botany in the Leland Stanford Junior
University. 12mo. Cloth. ix + 253 pages. Price by mail, $1.25;
for introduction, $1.12.

The special merit of this book is that it begins with the simple
forms, and follows the order of nature to the complex ones.

PLANT ORGANIZATION

By R. HALSTEAD WARD, formerly Professor of Botany in the
Rensselaer Polytechnic Institute, Troy, N.Y. Quarto. 176 pages.
Illustrated. Flexible boards. Mailing price, 85 cents; for
introduction, 75 cents.

ELEMENTARY METEOROLOGY

By WILLIAM MORRIS DAVIS, Professor of Physical Geography in
Harvard College. With maps and charts. 8vo. Cloth. xi + 355
pages. Mailing price, $2.70; for introduction, $2.50.

This work is believed to be very opportune, since no elementary
work on the subject has been issued for over a quarter of a
century. It represents the modern aspects of the science. It is
adapted to the use of advanced students, and will meet the needs
of members of the National and State Weather Services who wish to
acquaint themselves with something more than methods of
observation.

The essential theories of modern Meteorology are presented in
such form that the student shall perceive their logical
connection, and shall derive from their mastery something of the
intellectual training that comes with the grasp of well-tested
conclusions.

The charts of temperature, pressure, winds, etc., are reduced
from the latest available sources, while the diagrams freely
introduced through the text are for the most part new.

A.W. Greeley, retired Brigadier General U.S.A., and formerly
Chief of Signal Office, Washington:

"A valuable and timely contribution to scientific text-books."

Winslow Upton, Professor of Astronomy, Brown University:

"The best general book on the subject in our language."

Wm. B. Clark, Professor of Geology, Johns Hopkins University:

"An excellent book and of great value to the teacher of
meteorology."

David Todd, Professor of Astronomy, Amherst College:

"Clear, concise, and direct. To teach meteorology with it must be
a delight."

MOLECULES AND THE MOLECULAR THEORY OF MATTER

Department of Special Publioation. By A. D. RISTEEN. 8vo. Cloth.
Illustrated. viii + 223 pages. Retail price, $2.00

This work is a complete popular exposition of the molecular
theory of matter, as it is held by the leading physicists of
today. Considerable space is devoted to the kinetic theory of
gases. Liquids also are discussed, and solids receive much
attention. There is also a division discussing the methods that
have been proposed for finding the sizes of molecules, and here,
as elsewhere throughout the book, the methods described are
illustrated by numerical examples. The last division of the book
touches upon the constitution of molecules. The subject is
everywhere treated from a physical standpoint.

END OF AN INTRODUCTION TO CHEMICAL SCIENCE

INFORMATION ABOUT THIS ELECTRONIC EDITION

The original edition of this text was published by Ginn and
Company, Publishers, Boston, U.S.A. in 1896. The typography was
by J.S. Cushing and Co., Boston and the Presswork was by Ginn
and Co., Boston. The book was "Entered according to Act of
Congress, in the year 1887, by R.P. Williams, in the Office
of the Librarian of Congress, at Washington."

This electronic text was prepared by John Mamoun with help from
numerous other proofreaders, including those associated with
Charles Franks' Distributed Proofreaders website. Thanks to
R. Zimmerman, D. Starner, B. Schak, K. Rieff, D. Kokales,
N. Harris, K. Peterson, E. Beach, W.M. Maull, M. Beauchamp
J. Roberts and others for proofing this e-text.

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