Chapter 7

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 ½ 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 (½ ounce to 3 quarts) is mixed with 10¼ 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 £3,150,000, of which the United Kingdom consumed 23,000 tons, representing a value of nearly £1,000,000.

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 £4 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.

* * * * *

REDUCTION OF OXIDIZED IRON BY CARBONIC OXIDE.

IT is well known that when the heat is sufficient, carbonic oxide reduces the oxide of iron to metal with the production of carbon dioxide (carbonic acid). On the other hand, at lower temperatures carbon dioxide oxidizes metallic iron, forming carbonic oxide. J. Lowthian Bell's celebrated researches (see SCIENTIFIC AMERICAN, p. 199, March 31, 1883) established the point of equilibrium where in the presence of both monoxide and dioxide the reducing action of the one just counterbalances the oxidizing action of the other.

At the suggestion of Prof. R. Akermann, of Stockholm, C.G. Särnstrom has conducted a similar series of forty-five experiments, the expense being borne by the Jernkontor. About 1 gramme of oxide of iron was placed in a porcelain boat, and slid in a porcelain tube 18 millimeters (¾ inch) in diameter and 635 millimeters long (25 inches). This was exposed to the action of a current of mixed carbon dioxide and monoxide made by heating oxalic acid and concentrated sulphuric acid. It was mixed with carbon dioxide as required, then analyzed, and preserved in gasometers holding 66 liters. Before using, it is passed over phosphorus and chloride of calcium, and through sulphuric acid. The porcelain tube and boat were heated to from 300° to 600° C. (572° to 1,652° Fahr.) while the gases were passing, and then the state of oxidation determined. It was found that the larger the quantity of dioxide the higher the degree of oxidation, and the larger the proportion of monoxide the lower the degree of oxidation.

The details of the experiment indicate that a saving of fuel in the blast furnace could best be accomplished by the use of a very hot blast, introducing some carbon monoxide into the blast, provided, of course, that this gas can be made outside of the blast furnace more cheaply than inside of it. Nevertheless, 643 lb. of carbon must be burned to every 1,000 lb. of iron reduced, if carbonic oxide is exclusively employed.--_Stahl und Eisen_.

* * * * *

ON THE ADULTERATION OF SOAP.

By Dr. H. BRACKEBUSCH.

The importance of soap as an indispensable article in the household has not restrained the adulterators from making it a favorite object of their operations, and at the present day soap is only very rarely what it should be, the alkaline salt of a fatty acid with about 15 per cent. of water, which may be increased in case of soft soaps to 30 per cent. at most. The amount of moisture is an immediate signal for adulteration. Of all substances that can be used to adulterate soap, water is of course the cheapest, and as it is also harmless, this was the first point where manufacturers made use of their knowledge. The percentage of water was raised to 26 or 28 per cent., and now nearly all the ordinary soaps contain that amount when they leave the factory. At first the retailers objected to this method, because they had to suffer the loss so far as it dried out and lost weight in the store.

The next point was to find some substance that would prevent this rapid drying, and it was very soon discovered that those soaps that contained an excess of lye retained moisture longer. Henceforth it was only necessary to use lyes of extra strength so as to obtain a large yield of soap containing an excess of water. The results of this ingenious method are before us; in the shops of the soap dealers the bars of soap become coated with a crust of white crystals, which is nothing but soda. If a few drops of corrosive sublimate be dropped on these crystals, a red spot will at once be produced by the formation of mercuric oxide. In addition to the deception of the public who buy such soaps, this alkali destroys clothes washed with it, as the fiber of the tissues is directly attacked by it, while the proper action of the soap depends on its enveloping the particles of dirt and carrying them off.

Soap is subject to another kind of adulteration called filling, or weighting. Soapstone and similar mineral substances are added to the finished soap to increase its weight. But it may be added that this fraudulent weighting is rare. Large establishments cannot take the risk of being detected in such avaricious practices, and small ones scarcely have the apparatus at their disposal for making a uniform mixture which will not arouse suspicion.

Now soaps are frequently found in the market that scarcely deserve this name. Mineral soap, cold water soap, etc., are the names inscribed on the placards behind which is buried a preparation consisting for the greater part of water-glass. The well-known water-glass is a silicate of soda or potash dissolved in free or caustic soda, or potash. There was a time when it excited great hopes, and its introduction into the household for washing was dreamed of, but it was soon found that its caustic properties made their appearance at a relatively low temperature. Hence we often find the notice, "TO BE USED COLD," printed in bold letters on the wrappers. This product is obtained by thickening water-glass with stearine, oleine, or any other easily saponifiable fat. As it takes but very little of the substances named to make an article closely resembling soap, of course the product is very cheap. There does not seem to be any limit to the amount of water in it; at least the author found in one kind of mineral soap from Berlin 58 per cent. of water. Water-glass soaps do not dissolve readily in water, they make but little suds, and render the skin hard and unpliable. Admitting that they are suitable for many purposes, nothing can be said against their sale so long as they appear under names which preclude their being confounded with other soaps. Nevertheless, there is always this danger--that water-glass may come into general use in making soap, and this is to be deplored. Water-glass soaps are easily recognized by their insolubility in moderately strong alcohol, the water-glass remaining behind in a gelatinous form.

Great deception has been practiced under such names as "almond soap," etc. Fortunately the difference between various kinds of fat are not very great from a chemical point of view, although it is always an unpleasant thought that the fat from animals that have died may return to the house in the form of soap. A white or yellow soap having a good smell is not made from bad fat, and hence is more appetizing.

A method formerly much in use consisted in mixing green soap with starch paste, a mixture that could not be detected by the naked eye, especially if colored with caramel. On attempting to dissolve it in ordinary burning alcohol, a white coagulum forms.

From the foregoing it is sufficiently evident that those who buy soap to sell again have every reason to keep a sharp lookout on those who furnish them with soap.--_Polyt. Notiz._

* * * * *

BOVINE AND HUMAN MILK: THE DIFFERENCE IN ITS ACTION AND COMPOSITION.

By C. HUSSON.

M. Meynet, in a remarkable report upon condensed milk, has raised a question which it is important to have solved in the interests of infants. This is my excuse for presenting to the French Society of Hygiene certain observations on this subject.

Is woman's milk richer in fatty matters and sugar in proportion to the caseine than that of the cow? Is the affirmative, sustained by a large number of chemists, a mistake that ought to be corrected?

Such is the question that needs to be answered.

In my last work on milk, my aim was to report new experiments, and hence I gave only the analysis of M. Colawell. By the side of the essays of MM. Doyère, Millon, Commaille, and Wurtz, I put those of Liebig, and quoted an interesting chapter written on this question by M. Caulier, in Dechambre's Encyclopedic Dictionary. These are the authorities upon which to base any opposition to the analyses of Boussingault, Regnault, Littre, and Simon, savants of no less renown.

The differences are easily explained.

Woman's milk is rarely to be had in sufficient abundance to make a complete analysis of it. In the country especially a few precious drops, obtained with difficulty, are carried off in a thimble to be placed under a microscope, where the number of fat globules are counted, and it is examined to see if they are not mixed with globules of colostrum.

It will be necessary at the outset to know whether the analyses given refer to milk drawn from the breast before nursing, or at the end. In the former case there will be an excess of caseine, in the second an excess of fat present. This is the reason that in nursing infants the intervals should not be too long, or the child will not be able to empty the breast completely, and it will obtain a milk too rich in caseine, too poor in butter, and one that it cannot digest.

This is the first proof of the importance of fatty matters for the alimentation of babes.

Let us turn to the second.

At birth, when the milk is still in a state of colostrum, the fluid contains a variable quantity of albumen coagulable by heat, much less caseine, and an excess of butter and sugar.

Cow's milk, immediately after calving, contains more butter and less caseine than milk produced some time later, when the specific character of ruminants begins to appear in the calf, that is to say, when it commences to graze the milk coagulates in the stomach. As in other mammals, an excess of fat helps digestion by subdividing the caseine and emulsifying it. But the milk of an animal recently calved is reserved for its young, and it is not until the time of weaning that the lacteal fluid is offered for human consumption.

Thus it is that the nursling of a day receives milk many months old and heavily loaded with caseine. This milk it cannot digest because the emulsifying element, the fat, is not present in it in sufficient quantity in proportion to the coagulable matter. We must not forget either that the difference in coagulation holds also with respect to difference in the age and in the kind of animal. Just so the rennet of a sucking calf has a greater power of coagulating cow's milk than that of a sheep, and _vice versa_.