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List Of Contents | Contents of An Introduction to Chemical Science
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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.

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