192 M. Chevreul on Fatty Bodies, and [Sept. 



simple principle, but as a combination of the above two princi- 

 ples, which may be separated without alteration. One of these 

 substances melts at about 45°, the other at 100° ; the same quan- 

 tity of alcohol which dissolves 3*2 parts of the oily substance 

 dissolves 1*8 only of the fatty substance ; the first is separated 

 from the alcohol in the form of an oil, the second in that of 

 small silky needles. We perceive that the above substances 

 differ as much from margarine and fluid fat as natural fat differs 

 from that which has been saponified. 



Each of the constituents of natural fat was then saponified by 

 the addition of potash ; and an accurate description is given of 

 the compounds which were formed, and of the proportions of 

 their constituents. The oily substance became saponified more 

 readily than the fatty substance; the residual fluids in both cases 

 contained the sweet oily principle ; but the quantity that pro- 

 ceeded from the soap formed of the oilu substance was four 

 Or five times as much as that from the fatty substance ; the 

 latter soap was found to contain a much greater proportion of 

 the pearly matter than the former, in the proportion of 7*5 to 

 2-9; the proportion of the f aid fat was the reverse, a greater 

 quantity of this being found in the soap formed from the oily 

 substance of the fat. 



When the principles which constitute fat unite with potash, it 

 is probable that they experience a change in the proportion of 

 their elements ; this change developes at least three bodies, 

 margarine, fluid fat, and the sweet principle; and it is remark- 

 able that it takes place without the absorption of any foreign 

 substance, or the disengagement of any of the elements which 

 are separated from each other. As this change is effected by 

 the intermedium of the alkali, Ave may conclude that the newly 

 formed principles must have a strong affinity for salifiable bases, 

 and will in many respects resemble the acids ; and, in fact, they 

 exhibit the leading characters of acids in reddening litmus, in 

 decomposing the alkaline carbonates to unite to their bases, and 

 in neutralizing the specific properties of the alkalies. 



M. ChevreuVs Fourth Memoir* 



The subject of M. Chevreul's fourth paper is the action of 

 certain salifiable bases upon hog's-lard, and the capacities for 

 saturation of margarine and fluid fat. Having already pointed 

 out the analogy between the properties of acids and the prin- 

 ciples into which fat is converted by means of the alkalies, the 

 next object was to examine the action which other bases have 

 upon fat, and to observe the effect of water, and of the cohesive 

 force of the bases upon the process of saponification. The sub- 

 stances which the author subjected to experiment were soda, 

 the four alkaline earths, alumine, and the oxides of zinc, copper, 



* Abstracted from Ann, de Cliiui, xciv. 225. 



