In connection with this subject, Mulder observes that "when salad oil is conveyed into the stomach, it may pass unchanged into human fat, for both consist of margarin and olem, although in different proper tiona; and as margarin and olein are found in many vegetables used for food, nothing is more simple than to assume that these substances are directly transferred, without change, into the fate of the animal body.
" But if these game vegetables are eaten by a sheep, the olein and margarin must undergo P01110 change in the body of the animal, since mutton-fat contains a large amount of stearin. In this case the change is easily understood, for 2 eq. margaric acid (C„, 0„) =1 eq. ste,aric acid (C„, 0,) + 1 eq. oxygen. Thus, from two equivalents of margaric acid one equivalent of stearic acid is produced, and one equivalent of oxygen is given off in all probability such n &oxidation of the margaric acid in the food of the sheep is really effected ; and on the contrary, when mutton-fat is used fur food by man, stearic acid is most probably converted into margaric acid by the absorption of oxygen." It is now believed by our first physiologists, that the neutral fa* taken as food do not directly form fatty tissue, but that they enter the blood in a saponified state. In fact the alkaline character of the bile as it enters the duodenum renders it impossible for the fat to enter the blood without undergoing this change. If it be saponified, we readily understand how compounds of fatty acids and soda should exist In the blood and in various parts of the body. When a soda soap however exists in the blood, it cannot form a neutral fat, such as margarin or olein, without combining with glycerin. This leash,, to the inquiry, in the first place, whether the soaps meet with glycerin ; and secondly if they do, whether the glycerin would combine with the fatty amps and form neutral fats. There is good reason for believing that both thee° questions may be answered in the negative, for the glycerin set free when the soda-map is formed, is most probably at once decomposed ; and further, glycerin will not remove the soda from the fatty acid and form a neutral fut.
It has been suggested by Mulder, that although glycerin will not enter into this combination, the oxide of lipvle in a =scent state may do so, and that in this manner the fatty acids may be converted into neutral fats, and deposited in the cellular theme, and other par* of the body. We have already shown that (according to the opinion of Berzelius) glycerin is the oxide of the radical (C, I1,) lipyle. The second oxide of this radical exists In lactic acid, which is supposed by the great majority of chemists to be present in most parts of the body. When lactic) acid (C, I1, 0,) is sublimated, we obtain a white subli mate, the composition of which is C, 11, 0,; while the composition of the oxide of lipyle is C, 0.
It may happen that there are causes of &oxidation at work in the system, by which some of the substances usually converted into lactic acid are made to produce oxide of lipyle, which in the nascent state unites with the fatty acid'', forming neutral fate.
Hence in all probability the neutral feta are not deposited directly and unchanged in the cellular tissue, but are first saponified, and entering the blood as mnrgarate and oleate of soda, are again reduced to neutral fate by the influence of lactic acid.
The next question for our consideration is the formation of fat —a subject which has given rise to much angry and intemperate diacusaion between the loading chemists of France and Germany. Dumas, who may be regarded as the representative of the French school, maintain,' that all the fat of animals originats in and is obtained from plants ; while Liebig, on the contrary, maintains that a portion of it is formed by the animal itself, from starch, sugar, and gum. The goose was the animal respecting which the dispute originated. When fattened with Indian corn, the starch must, according to Liebig, have been changed into fat, because he had found but a minute quantity (about 1 part in 1000) of fat in that kind of grain. DU/1111.9 however extracted 9 per cent, of fat from Indian corn (or ninety times as much as Liebig), and thus he found in the food which the goose had eaten much more fat than had to be accounted for. The actual fact is, that the amount of fat in this grain is so variable that no conclusion can be drawn from the experiment. Liebig quotes many examples of substances which, although they contain little fat, are well known by experience to be especially fit for fattening the animal body. Rice, per* beans, mid potatoes arc all known to possess this property ; yet rice gives only 01 to O'S per cent, of matters soluble in ether (the ordinary means of determining the amount of fit) ; pens 1.20 to 2'1 ; beans 0'70, and dried potatoes 0.35 per cent Thus any animal that has eaten 1000 pounds of one of these substances may obtain from them 2 to 8, 12 to 21, 7, or 3i pounds of fat respectively. Ito makes; the following calculations :—Three pigs to be fattened in Thirteen weeks require 1000 pounds of peas, and 6525 pounds of boiled potatoes, the latter being equal to 1638 pounds of dry potatoes. These contain in all 26 pounds of fat, the peas yielding 21 pounda; and the potatoes 5. One fattened pig gives on an average 50 to 55 pounds of fat, the three yielding 150 to 165 pounds. Each pig before fattening contains on an average 18 pounds of fat—that is, 54 pounds for the three. If to thee° 54 ponnda be added 26 pounds contained in the food, we get 80 pounds; and if we subtract these from 150 to 165 pounds, there is a remainder of 70 to 85 pounds of fat produced from the starch, &c., of the food. Liebig's opinion is further strengthened by the circumstance that some fats are undoubtedly produced in the body, as, for instance, the fats peculiar to the brain, CholesPrrin, Celine, Phoernine, ate. To obtain these from other fat requires just as much a new arrangement as if they were produced from starch ; hence, in a scientifle point of view, there is nothing improbable in the supposition that 'wizards are able to produce fats.