190 M. Chevreul on Fatly Bodies, and [Sept. 



By separating the water, evaporating it, and treating the solid 

 residue with alcohol, a quantity of yellow colouring ma ter is 

 procured, while the soap of barytes was left pure and colourless. 

 The next object was to ascertain the composition of this soap : 

 for this purpose a portion of it was put into a platina crucible, 

 which was then gradually raised to a red heat, by which a quan- 

 tity of carbonate of barytes was obtained, combined with a 

 minute portion of carbon; sulphuric acid was added, and by 

 comparing the quantity of sulphate of barytes formed with the 

 soap employed, he determined the composition to be, 



Fluid fat 77-55 100-00 



Barytes 22-45 28'95 



100-00 



By decomposing this barytic soap with sulphuric acid, the 

 fluid fat is separated in a very pure state, and was supposed, 

 like the pure margarine, to possess the power of reddening 

 litmus. 



The Jtuid fat seems to be capable of forming two combinations 

 with potash ; the first, with a minimum of alku'i, which is gela- 

 tinous, soluble in alcohol, but insoluble in water ; the other is 

 soluble in water, but appears to be decomposed into potash and 

 into the other species of soap, when it i,5 diffused through a 

 large quantity of fluid. Water appears to exercise the same 

 kind of action upon the soap of the fluid fat as u^on that of 

 margarine ; that is, it reduces it to potash and the Buper-s< op ; 

 a greater quantity of fluid and a longer space of time are, how- 

 ever, necessary to complete the operation , The experiments 

 which were performed m order to investigate all these points 

 require a very long space of time for their completion, some of 

 them as much as 18 months, and they are among the most 

 elaborate in the whole science of chemistry. The general con- 

 clusions which the author deduces from his experiments are, 

 that the soap formed by the union of laid and potash is not a 

 mere binary compound, but is composed o 'margarine, fluid fat, 

 a volatile oil, and an orange-coloured matter. These bodies are 

 saturated with potash; the first two exr in a much greater 

 proportion than the last two, and maybe regarded as the essen- 

 tial constituents of soap. The experiments which have been 

 related above, and the conclusions to which they lead, enable 

 us to explain the manner in which soap acts when it removes 

 grease from stuffs. It in fact depends upon a portion of the 

 alkali being set at liberty, and thus being enabled to act upon 

 fatty substances, in consequence of the decomposition of the 

 soap of margarine by the addition of water. The same decom- 

 position may be effected in the soap of the fluid fat, provided it 

 be diluted with a sufficient quantity of water; but probably 



