266 
DR. MARCET ON THE IMMEDIATE PRINCIPLES OF 
When boiled in alcohol, human feces yield an abundant extract, and if small 
quantities of alcohol be used at a time, and the extract rapidly filtered through a 
rough, clean cloth, nothing remains on the filter but a brown mass, devoid of smell, 
insoluble in ether, and yielding to boiling water nothing but ammoniaco-magnesian 
phosphates, which can be obtained crystallized by slow evaporation. 
It was found necessary to operate each time on the whole evacuation, which was 
treated with boiling alcohol of specific gravity 845 : upwards of fifty human evacua- 
tions were examined, about a pint and a half of alcohol being required for each 
operation ; the feces were previously mixed with a little water, to facilitate the 
action of the alcohol when their consistence was too solid. This alcoholic extract 
had a very distinct smell of the matter examined, and a strong acid reaction, showing 
that one or more acid principles exist as constituents of human evacuations. The 
alcoholic solution was set aside for twenty-four hours, when an abundant deposit 
was found at the bottom of the beaker ; the fluid was decanted, and the deposit 
collected upon a filter. The alcoholic solution still possessed an acid reaction ; it 
had a slightly viscous consistence, and a dark olive-brown colour. This fluid was 
treated by a variety of processes, which yielded no satisfactory result, until milk of 
lime having been added, with the view of precipitating the fatty acids it might con- 
tain, as I had done on a previous occasion to obtain the fatty acids of the blood*, a 
distinct precipitate occurred of a yellowish-brown colour, subsiding after a few 
minutes, and leaving a clear brown straw-coloured fluid ; this precipitate was col- 
lected, after an hour or two, upon a filter. It had a viscous nature and a yellowish- 
brown colour. The filtrate was set aside, and the lime precipitate left to dry upon 
filtering-paper. When the excess of moisture had thus been removed, and the 
precipitate obtained had become comparatively dry, it was transferred to a small 
glass phial, and agitated with ether: in some instances I used boiling ether, but 
soon found it was unnecessary, so that cold ether was generally employed. The 
contents of the phial were next filtered, and a clear yellow ethereal solution thus 
obtained. The lime precipitate was then washed with ether, and the entire solu- 
tion finally allowed to evaporate spontaneously. After a period varying from 
one to three days, the fluid was found to contain a quantity of beautiful silky cry- 
stals, collected in masses or tufts adhering to the sides and bottom of the beaker, 
gradually increasing in size and numbers, and throwing out in every direction 
extremely fine and light ramifications. The mother-liquid having been decanted, 
and the substance placed upon filtering-paper, the crystals were found to be so fine 
and delicate as to be crushed by the mere weight of the fluid contained between 
them, so that, when dry, their crystalline structure had nearly disappeared, the sub- 
stance having assumed the appearance of light flattened brittle scales. The crystals 
thus obtained are far from pure, being mixed with an oily yellow matter, which 
* Recherches sur la Nature des Graisses qui se trouvent dans le Sang. Bibliotheque Universelle de 
Geneve, 1851. 
