Scientific American Supplement, No. 392, July 7, 1883

V >> Various >> Scientific American Supplement, No. 392, July 7, 1883

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My own estimation of the amount of glycerine in different olive oils, by
Koenig's method, has shown, unfortunately, that the percentage may vary
from 1.6 to 4.68, according to the origin and quality of the oil. In
like manner the estimation of the oleic acid, which was conducted
essentially in the manner proposed by Koenig, showed that the amount of
oleic acid in different olive oils varied from 45 to 54 per cent. But
since cotton seed oil, for example, which is most frequently used to
adulterate olive oil, contains 5 per cent. of glycerine, and 59.5 per
cent. of oleic acid, it is easy to see an admixture of cotton seed oil
cannot be detected by this method, which appeared to be so exact.

The method of analysis that I am about to describe is based chiefly upon
the determination of the melting point of the fatty acids contained in
the oils, and upon their solubility in a mixture of alcohol and acetic
acid.

The oils employed in adulterating olive oil, and to which regard must be
had in testing it, are the following: Cotton seed oil, sesame, peanut,
sun flower, rape, and castor oils. The tests for the two last named
have hitherto never presented any difficulty, as rape seed is easily
detected, owing to the sulphur in it, by saponifying it in a silver
dish, and castor oil by its solubility in alcohol. But in recent times
another product has come into the market called sulphur oil or pulpa
oil, obtained by extracting the pressed olive cake with sulphide of
carbon. This also gives a sulphur reaction when saponified, while it
resembles castor oil by its solubility in alcohol. When this oil is
mixed with ordinary olive oil, it can easily deceive any one who uses
the ordinary tests.

My method of testing olive oil is as follows:

First, the so-called elaidine test is made, and then the test with
nitric acid. About 5 c. c. (a teaspoonful) of the oil is mixed in a test
tube with its own volume of nitric acid, spec. gr. 1.30, and shaken
violently for one minute. At the expiration of this time the oils will
have acquired the following colors: Olive oil, pale green; cotton seed
oil, yellowish brown; sesame, white; sun flower, dirty white; peanut,
rape, and castor oils, pale pink or rose.

As soon as the color has been observed, the test glass is put in a water
bath at the full boiling temperature and left there five minutes. It was
found that the action of nitric acid upon cotton seed and sesame oil was
the most violent, sometimes so violent as to throw the oil out of the
glass. At the end of another five minutes after the test tube is taken
out of the water bath, the following colors are seen: olive and rape
oils are red; castor oil is golden yellow; sun flower oil, reddish
yellow; sesame and peanut, brownish yellow; cotton seed, reddish brown.

After standing 12 to 18 hours at about 60 deg. Fahr. the olive, rape, and
peanut oils will have solidified; sun flower, castor, and cotton seed
will be like salve (sticky), while sesame will remain perfectly liquid.
Mixtures of olive oil with small quantities of cotton seed or sesame are
distinguished by this characteristic--that, although the whole mass,
which is darker in color than olive oil, solidifies at first, at the end
of 24 or 36 hours a brown oil will be found floating upon the surface of
the solid mass, while the lower strata exhibit the yellow color of pure
olive oil. Oil of rosemary has no effect when shaken with cold nitric
acid, and imparts to it only a slightly darker color on heating. Oils
treated with lye act just like pure oils.

Far the purpose of determining the melting point of the fatty acids, 10
grammes of oil were saponified with 5 grammes of caustic potash on the
water bath; some water and alcohol being added. After all the alcohol
had been expelled the soap was dissolved in hot water, and the fatty
acids separated from the clear solution by adding hydrochloric acid.
After prolonged heating these acids will swim on the salt solution as
a perfectly clear oil, a portion of which is then put into a little,
narrow, thin walled tube and allowed to solidify. The point at with it
melts and solidifies is determined by putting this tube in a beaker
glass filled with water and warming with a small flame. A thermometer
is placed _in_ the fatty acids and moved gently about during the
observation, and the point accurately observed at which the whole mass
becomes perfectly clear, and also when the mercury bulb begins to be
clouded. It was found that the acids from pure olive oil melt between
261/2 and 281/2 deg. C. (= 80 deg. to 83 deg. Fahr.) and solidify at a point not lower
than 22 deg. C. (72 deg. Fahr.). The melting point of the fatty acids in the
oils used to adulterate olive oil differs considerably from this. The
melting and solidifying points of the acids in cotton seed, sesame,
and peanut oils lie considerably higher, those of sunflower, rape, and
castor oils decidedly lower than those of olive oil.

The melting and solidifying points of these acids are as follows:

Cotton seed melts at 38.0 deg.C. solidifies 35.0 deg.C.
Sesame do. 35.0 do. do. 32.5 do.
Peanut do. 33.0 do. do. 31.0 do.
Sunflower do. 23.0 do. do. 17.0 do.
Rape do. 20.7 do. do. 15.0 do.
Castor oil do. 13.0 do. do. 2.0 do.

The above figures differ so much from those of olive oil, that
adulteratious carried to the extent that they are in trade can easily
be detected by the aid of an estimation of the melting point, for a
Gallipoli olive oil, mixed with 20 per cent. of sunflower oil, melted at
24 deg. C. and solidified at 18 deg. C. (of course, the fatty acids are meant).
A Nizza oil, mixed with 20 per cent. cotton seed oil, melted at 311/2 deg. C.
and solidified at 28 deg. C. A Gallipoli oil with 33-1/3 per cent. of rape
oil melted at 231/2 deg. C. and solidified at 161/2 deg. C. When 0.50 per cent. of
rape is added, it melts as low as 20 deg. and solidifies at 131/2 deg. C., etc.

In testing the solubility of the fatty acids in alcohol and acetic acid,
I employ the method proposed by David (in _Comptes Rendus_, 1878, p.
1416) for estimating stearic acid.

It depends upon the principle that when acetic acid is poured drop by
drop into an alcoholic solution of oleic acid, there comes a time when
all the oleic acid separates, but stearic acid, which is insoluble in
a mixture of alcohol and acetic acid, remains insoluble if the mixture
contains oleic acid.

The following manipulations are adopted in testing olive oil: Equal
parts of glacial acetic acid and water are mixed in a bottle. Then 1
c.c. of pure oleic acid, 3 c.c. of 95 per cent. alcohol, and 2 c.c.
of acetic acid are put in a small tube graduated in tenths of cubic
centimeters. The solution should remain clear; on adding another
one-tenth c.c. of acetic acid it becomes turbid, and when 1 c.c. of
oleic acid (or at first even more) floats on the mixture of acid and
alcohol, the liquid is ready for use. If this is not the case, the
proportions (of acetic acid and alcohol?) must be varied until the
addition of one-tenth c.c. of the former will cause all the oleic
acid to separate. The proportions having been ascertained from
these preliminary experiments, the alcohol and acid are then mixed
accordingly, e.g., 300 of alcohol to 225 of acid. One or two grammes
of stearic acid are added to the alcoholic acetic acid, and the clear
supernatant liquid used for the experiments.

One cubic centimeter of the oil (acids) to be tested is put in the tube,
and 15 c.c. of alcoholic acetic acid added, well shaken, and the whole
left to stand quietly at 15 deg. C. (60 deg. Fahr). If the olive oil is pure,
the acids dissolve to a clear solution that remains so. Cotton seed
oil is insoluble, and the solution obtained by heating the solution
solidifies at 60 deg. Fahr. to a white jelly. Sesame and peanut oil react
in a similar manner. Sunflower oil dissolves, but at 60 deg. a granular
precipitate falls. Rape oil is entirely insoluble and floats like oil on
the surface. Castor oil on the contrary dissolves completely, just like
olive oil, and hence cannot be detected therein by this method. To
detect this oil we must take the melting point of the acids along with
the solubility of the oil itself in alcohol.

Olive oil when mixed with 25 per cent. of cotton seed oil yields a
granular precipitate, and so does 25 per cent. of sesame. Smaller
quantities cannot be detected by these methods. For rape oil the limit
is 50 per cent., and in smaller quantities the oil does not collect on
the alcoholic solution. The decided lowering of the melting point of
the fatty acids in combination with the sulphur reaction, and the
insolubility of the oil in alcohol, also furnish a method of detecting
when present in smaller quantities in olive oil.

Although I am well aware that I am making public a research that is by
no means free from objections, I nevertheless believe that it may be of
use to those who have to undertake the ticklish and intricate analyses
of commercial fats.--_Translated from the Chemiker Zeitung_, p. 355.

Leipsic, Jan., 1883.

* * * * *

ON THE THEORY OF THE FORMATION OF COMPOUND ETHERS.

In a note presented to the Industrial Society of Mulhouse, A. Pabst
discusses the different stages in the formation of compound ethers, as
Williamson has explained the production of ordinary ethers by the action
of sulphuric acid upon alcohol. Pabst has observed that the compound
ethers are formed in an analogous manner. If alcohol, sulphuric acid,
and acetic acid are heated together, acetic ether, we know, is formed.

Pabst has shown that it takes place in three stages. In the first stage,
ethyl sulphuric acid and water are formed; in the second, acetate of
ethyl with the reproduction of sulphuric acid, which again converts a
fresh quantity of alcohol into ethyl sulphuric acid.

(1) C_{2}H_{5}OH+HO,SO_{2}OH = C_{2}H_{5}O,SO_{2}OH+H_{2}O.
(Alcohol.) (Sulphuric acid.) (Ethyl sulphuric acid.)

(2) C_{2}H_{5}O,SO_{2}OH+C_{2}H_{3}O,OH =
(Ethyl sulphuric acid.) (Acetic acid.)

C_{2}H_{5}O,C_{2}H_{3}O+HO,SO_{2}HO.
(Acetate of ethyl.) (Sulphuric acid.)

Pabst proved this by letting methyl sulphuric acid act upon a mixture of
acetic acid and ethyl alcohol. He obtained by this process acetate
of methyl and ethyl sulphuric acid. By the continued action of ethyl
alcohol and acetic acid upon this mixture, of course, acetate of ethyl
was formed. At the conclusion of the operation there was no longer any
methyl sulphuric acid present in the liquid.

In the course of his investigations, Pabst was led to a very practical
method for preparing acetate of methyl, which consists in heating ethyl
sulphuric acid to 135 deg. or 140 deg. C, and allowing a mixture of equal
molecules of strong alcohol and acetic acid to flow into it.

The details of his experiments and the method of purification will be
published by the society.

* * * * *

A GREEN OR GOLDEN COLOR FOR ALL KINDS OF BRASS.

By E. PULCHER.

The French brass castings and articles of sheet brass are made of cheap,
light colored brass, and possess a fine golden color which is not
produced by gold varnish, but by a coating of copper. This gives them a
finer appearance, so that they sell better.

This golden color can be easily produced at very little expense and with
but little trouble by the following process. Fifty grammes of caustic
soda and 40 grammes of milk sugar are dissolved in a liter of water
and boiled for a quarter of an hour. The solution is clear as water at
first, but acquires a dark yellow color. The vessel is next taken
from the fire, placed on a wooden support, and 40 grammes of a cold
concentrated solution of blue vitriol stirred in. A red precipitate of
suboxide of copper is at once formed, and by the time the mixture cools
to 167 deg. Fahr., the precipitate will have settled.

A suitable wooden sieve is placed in the vessel, and on this the
polished articles are laid. In about one minute the sieve is lifted up
to see how far the operation has gone, and at the end of the second
minute the golden color is dark enough.

The sieve and articles are now taken out, and the latter are washed
and then dried in sawdust. If the brass is left longer in the copper
solution, in a short time a fine green luster is produced, becoming
yellow at first and then bluish green. After it turns green, then the
well-known iridescent colors finally appear. To obtain uniform colors
it is necessary that they be produced slowly, which is attained at
temperatures between 135 deg. and 170 deg. Fahr.

The copper bath can be used repeatedly and can be kept a long time if
bottled up tightly without change. After it is exhausted it can be
renewed by adding 10 grammes of caustic soda, replacing the water that
has evaporated, heating to boiling, and adding 25 grammes of a cold
solution of blue vitriol.

Similar operations with other well known reducing agents, such as
tartrate of soda, glycerine, etc., do not give such good colors, because
they do not precipitate the copper solution so rapidly and at so low a
temperature.

If the rinsed and pickled brasses are dipped for five minutes in a three
per cent. neutral solution of cocoa nut oil soap, and then washed with
water again before they dry, the coating gains in permanence.

Brass articles that have to be cleaned frequently should be covered with
oil of turpentine, or thin English copal varnish.--_Neueste Erfind_.

* * * * *

VINEGAR.

Hermann Kratzer, of Leipsic, communicates the following practical
information on the clarification and purification of vinegar to the
_Neueste Erfindungen und Erfahrungen_:

If vinegar has an unpleasant odor, which is rarer now that the vinegar
manufacture has reached such a state of perfection, it may be removed as
follows: Well burned and finely pulverized wood charcoal is put into
the bottles containing the vinegar, the proportions being 8 grammes of
charcoal to a liter of vinegar, or one ounce to the gallon. It is shaken
several times very thoroughly, then left standing three or four days,
and the vinegar filtered through a linen cloth. Vinegar treated in this
manner will be found to have completely lost its unpleasant odor.

I have found that when I used blood charcoal or bone coal in place of
wood coal it was still more efficient; but it must be mentioned that
when they are used they must be purified as follows before using:
Charcoal from blood contains potash and hence it is necessary to wash it
with distilled water and dry it before using it. Bone coal (also called
bone black, animal charcoal, etc.) contains on an average 10 per cent.
of nitrogenous and hydrogenated carbon, 8 per cent. of carbonate of
lime, 78 per cent. of phosphate of lime, besides phosphate of magnesia,
sulphate of lime, soluble salts, etc. Before using, it should be treated
with dilute hydrochloric acid until it does not effervesce any more. The
bone coal is then left to stand for 24 or 30 hours and at the end of
this time is washed with distilled water until the wash water no longer
reddens a blue piece of litmus paper, i.e., until every trace of
hydrochloric acid has been removed from the bone coal. Wood charcoal
may be treated in like manner. When this coal is perfectly dry it is
employed in the same proportions as the other, 8 to 1,000, the operation
being exactly the same.

He turns next to the clarification of the vinegar.

It happens everywhere that vinegar instead of being clear is sometimes
turbid. This is due to particles of yeast dissolved in the vinegar that
have not yet settled. To remove this kind of turbidity it is customary
to use oak or beech shavings that have been washed in hot water and then
dried. These shavings, which must be very long and extremely thin, are
put in a barrel with a second and perforated bottom, to a depth of 12
to 34 inches. The vinegar that runs through them deposits its slimy
constituents on the shavings and becomes perfectly clear, and presents
to the eye a pleasing appearance.

To this generally known method I would add a few more:

1. I take a 1/2 kilo of well pulverized _animal charcoal_ (black burned
bones) to 7/8 of a hectoliter of vinegar (1 lb. to 20 gallons), and stir
it well with a wooden rod; or, if the vinegar is in bottles, I shake it
a long time after putting the animal charcoal in the bottle, and repeat
it several times. After three or four days I finally filter the vinegar
through linen, when the filtrate will exhibit the desired clearness.

2. The best way to clarify vinegar is with _isinglass_. It is first
broken up, then swelled for a day in vinegar (17 or 18 grammes to the
liter), then 2 liters of vinegar are added and the mass boiled until the
isinglass is completely dissolved. Such a solution as this (1/2 ounce to
3 quarts) is mixed with 101/4 hectoliters (250 gallons) of turbid vinegar
and well stirred through it. After the expiration of five or six weeks
vinegar treated in this way has a beautifully clear appearance.

3. _Albumen_ can likewise be used to clarify it. The vinegar is boiled
with the albumen until the latter is completely coagulated, and then the
vinegar is filtered.

4. And finally _milk_ may be employed. For this purpose the milk is
skimmed, and 1 quart of milk added for every 68 quarts of vinegar,
the mixture well stirred and shaken. After the caseous portion has
coagulated (curdled) it is filtered as before, and in this case, too,
the product is a fine, clear vinegar.

We believe that these few experiments, so easily performed, and at so
small an expense, will prove useful to our readers in enabling them to
put their product in the market in an excellent condition and nicely
clarified.

* * * * *

THE ALIZARINE INDUSTRY.

At a recent meeting of the Manchester section of the Society of Chemical
Industry, Mr. Ivan Levinstein described the history and progress of the
manufacture of alizarine, from which are produced fast red, purple,
brown, and black dyes. He said alizarine was, until very recently, made
only from the root of the madder plant, of which the yearly crop was
70,000 tons, and represented an annual value of L3,150,000, of which
the United Kingdom consumed 23,000 tons, representing a value of nearly
L1,000,000.

Madder is now no longer grown for this purpose. The German chemists
found that alizarine produced from madder in undergoing certain
treatment gave a substance identical with anthracine, one of the
constituents of coal tar, and in 1869 the same chemists announced to
the world that they had accomplished the synthesis of alizarine from
anthracine. The effect of this discovery was to throw madder out of
cultivation.

Mr. Perkin, an English chemist, and Messrs. Graebe and Liebermann,
German chemists, almost simultaneously applied for patents in 1869,
in England, and as their methods were nearly identical they arranged
priorities by the exchanging of licenses. The German license became the
property of the Badische Aniline Company, and the English license became
the property of the predecessors of the North British Alizarine Company.
These patents expire in about two months, and the lecturer explained
that an attempt made by the German manufacturers to further monopolize
this industry (even after the expiry of the patent) proved abortive. He
also stated that alizarine, 20 per cent. quality, is sold to-day at 2s
6d. per lb., but that if the price were reduced by one-half there will
still be a handsome profit to makers, and that the United Kingdom is the
largest consumer, absorbing one-third of the entire production, and that
England possesses advantages over all other countries for manufacturing
alizarine--first, by having a splendid supply of the raw material,
anthracine; secondly, cheaper caustic soda in England than in Germany by
fully L4 per ton; thirdly, cheaper fuel; fourthly, large consumption at
our own doors; and, fifthly, special facilities for exporting.

The advantages derived from the development of the alizarine manufacture
here, it was stated, will benefit other collateral industries, such
as manufacture of soda, of ordinary sulphuric acid, bichromatic, and
chlorate of potash, articles used in this manufacture. The lecturer
considered that the difficulties attending the manufacture of alizarine
were now overcome, and with sufficient capital and competent chemists
English manufacturers must be successful.

He then proceeded to explain the source from which nearly all the
artificial coloring matters are derived, viz., gas tar; showing the
principal products of this wonderful, complex mixture, of which one
is anthracine. Alizarine manufacturers originally found scarcity of
anthracine; at present the supply is in excess of the demand, and the
price during the last 18 months has fallen from 3s. 6d. to 1s. per unit,
and the probabilities are that the supply will increase. The quantity of
gas tar now obtained the lecturer estimated at 500,000 tons per annum,
and the coal carbonized for gas making, 10,000,000 tons. This quantity
of tar suffices to produce 9,000 tons of 20 per cent. alizarine.

The lecturer then reviewed, in case of an increased demand for
anthracine, the probable new sources of obtaining increased supplies of
coal tar: (1) The destructive distillation of petroleum; (2) coke
ovens and blast furnaces; (8) the carbonization of coal for general
manufacturing purposes, using the coal and gas as fuel, and giving tar,
benzine, and ammonia as residues; and (4) distillation of coal with the
object of obtaining the principal products, tar and benzine, and as the
residual product, gas. This part of the lecture was important to dyers
and printers, the lecturer showing also, in a very interesting way,
in what manner manufacturers may very considerably economize their
consumption of coal.

The lecturer explained that while from one ton of coal there was
obtained on an average about 17 oz. of benzine, by the new method about
thirty times that amount can be got from the same quantity of coal.
He also considered in great detail the different processes of the
carbonization of coal, and of increasing the production of the different
important residual products of gas tar, and also the best method of
extracting the benzine. He showed samples of benzine which he produced
from gas obtained at the Rochdale Road Gasworks, and, further,
nitro-benzine, aniline, and coloring matters, which he had made from
this gas benzine.

The lecturer also discussed the effect of the probable increased
production of tar, ammonia, benzine, etc., as affecting gas companies,
and said it was anticipated they either would raise the price of gas or
change the present system of manufacture, which he considered probable.
The enormous increase in the production of ammonia, of which the larger
portion at present, as sulphate of ammonia, was used as a fertilizer,
would no doubt considerably reduce its value. It might even replace soda
for many purposes, and thus react on our alizarine industry.

He then proceeded to consider the manufacture of alizarine purpurine,
and divided its manufacture into four stages: 1, the purification of
crude anthracine; 2, the conversion of the purified anthracine into
anthraquinone; and 3, the production of sulpho acid of anthraquinone and
the conversion of this sulpho-acid into alizarine and purpurine. This
part of the lecture comprised a detailed explanation of the various
kinds of apparatus required, to be used which were beautifully got up,
complete working models having been prepared for the occasion. The
lecturer was of opinion that large consumers would be benefited if
makers would offer for sale only three distinct coloring matters--iso
or anthrapurpurine, and flavo-purpurine, leaving it to the dyers and
printers to produce for themselves the intermediate shades by mixing the
three colors; and he showed that by reason of the fastness of the shades
produced by these coloring agents varying considerably, the blue shade
(alizarine) being much faster then the orange shade (flavo-purpurine),
consumers were in many instances losers by using mixtures of alizarine
and flavo-purpurine.

In the course of the lecture many interesting specimens of various
products were produced and dilated upon, the lecturer fully describing
the process of purifying the crude anthracine and of the conversion of
the purified anthracine into anthraquinone.

* * * * *

THE PRESERVATION OF MEAT BY CARBONIC ACID.

Since 1874, when Professor Kolbe, of Leipsic, first published his
results on the antiseptic action of salicylic acid, he has made many
efforts to apply this acid to the preservation of meat, but he has
invariably found that after the lapse of a few days an unpleasant flavor
has been developed, which is not that of putridity. If putrid changes be
noticed, it is a sign that salicylic acid is in insufficient quantity,
for where it has turned putrid the meat is found to be no longer acid,
but alkaline. This leads to the assumption that meat is protected from
change by acids, even by gases of that kind; and in fact it was noticed
that beef--from 2 to 5 kilos. being taken--when placed in an earthen
vessel and loosely covered with a wooden cover, was long preserved from
putridity if the bottom of the vessel contained some hydrochloric acid,
nitric acid, or aqueous sulphurous acid. The meat, however, no longer
had the taste of fresh meat, but of such as had long lain in ice.
Experiments were therefore made with carbonic acid, and these proved
highly successful. The meat was placed in a cylinder of metal plate, and
suspended from a rod which crossed the upper part and the lower part.
A small tube serves to admit a current of carbonic acid from a Kipp's
apparatus. The lid, which rested in a circular trough of glycerine,
was traversed by a similar tube in its center, and both tubes could be
closed with India-rubber tubing and screw taps as soon as sufficient
carbonic acid gas had traversed the apparatus. At the end of seven,
fourteen, and twenty-one days it was found that the meat was still quite
good, and the soup prepared from it was in every respect excellent. At
the end of the fourth or fifth week the meat thus preserved in the gas
was still quite free from all putridity; but the broth prepared from it
no longer tasted so well as fresh bouillon. The experiments were not
extended over a longer time. Carbonic acid is thus shown to be an
excellent means of preserving beef from putridity and of causing it to
retain its good taste for several weeks. Mutton does not preserve so
well. In eight days it had become putrid; and veal is by no means so
well preserved as beef. The comportment of beef in an atmosphere of
carbonic acid, to which carbonic oxide has been added, is curious. A
number of cylinders were filled in the usual way with such a mixture and
opened at the end of two or three weeks; in each case the flesh had the
smell and taste of good, pure meat, but it was not of the gray color
which meat preserved in carbonic acid gas gradually takes, but appeared
in the interior, as well as on the outside, of a bright flesh-red color,
and on the surface here and there, there were white round masses of
fungoid growth of the size of a 20-pfenning piece, which were removed
with the slightest rubbing. The flesh lying just below these was found
to have the same bright red color as that already described. Meat which
had been for three weeks in such a gas mixture gave a broth which,
in good taste and freshness, could hardly be distinguished from
freshly-made bouillon; and the boiled meats could not be distinguished
either in appearance or taste. The property of carbonic acid to preserve
meat suggests a use for the large supplies of this gas evolved from the
earth in many localities. And it is as interesting to determine in
how far the gas could be of service as an antiseptic during surgical
operations.

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