310 Royal Society :— 
bodies to consider whether any, and what, steps should now be taken 
to procure the cdntinuance of the researches. 
March 12.—Major-General Sabine, Treas. and V.P., in the Chair. 
“On the Immediate Principles of Human Excrements in the 
Healthy State.” By W. Marcet, M.D., F.C.S. 
In a previous paper I had the honour of communicating to the 
Royal Society the results of a first series of investigations on the 
immediate principles of the feeces of man and animals ; since then I 
have continued my researches on human excrements, being most 
ably seconded by my assistant, Mr. Frederick Dupré, Ph.D. 
The new results obtained were the following :— 
1. Margarate of lime, phosphate of lime, and margarate of mag- 
nesia were discovered to be immediate principles of human evacua- 
tions, 
2. I found a new method for obtaining excretine, and its chemical 
formula has been established. 
3. The fact that vegetable food induces the presence of margaric 
acid in excrements has been confirmed. 
4. The existence of a comparatively large quantity of cholesterine 
in the spleen, which I had mentioned before as probable, has been 
confirmed. 
When human feces are exhausted with boiling alcohol, the fluid 
being rapidly strained through a cloth, a clear extract is obtained, 
which, on cooling, yields a deposit ; this substance, being collected 
on a filter, is partly soluble in boiling alcohol, and there remains un- 
dissolved a residue insoluble in ether and alcohol. The residue in 
question being boiled with a solution of potash, dissolves almost 
entirely, and the addition of hydrochloric acid induces the formation 
of a precipitate in the solution. On examining this precipitate, it 
was found to consist of a crystallizable substance fusing at 60° Cent. ; 
its structure and other properties were precisely those of margaric 
acid, 
The acid filtrate contained phosphoric acid and lime. From 
several quantitative analyses, I concluded that there was more lime 
than is required to combine with the phosphoric acid in the form of 
the neutral phosphate, the excess of lime being exactly that which 
was necessary to convert the margaric acid into a neutral margarate 
of lime, C,, H,,0,+CaO. Consequently it followed that the three 
substances existed in the form of margarate of lime and phosphate 
of lime as immediate principles of human feeces. 
The alcoholic filtrate from the deposit being allowed to stand for 
twenty-four hours, deposited another substance, of a nearly white 
appearance, and which proved to be margarate of magnesia. 
The peculiar action of a vegetable diet on human feeces was inves- 
tigated by means of experiments undertaken upon myself, when I 
observed that an entirely vegetable diet was attended with the form- 
ation of a large quantity of margaric acid in the excrements,—most 
probably not in the form of a margarate, but in the free state, inas- 
much as it was obtained from the decomposition, with hydrochlori¢ 
