DE. MAECET ON THE IMMEDIATE PEINCIPLES OF HUMAN EXCEEIVIENTS. 405 
tion was thus obtained. The residue left on the three filters, after being washed with 
cold alcohol and subsequently removed to capsules with the platina knife, was boiled in 
alcohol, the fluid being afterwards rapidly strained through calico. On cooling, a very 
small quantity of deposit occurred in the solutions No. 1 and No. 2 ; solution No. 3 
yielded rather more : the fluids were subsequently evaporated to dryness and the residue 
boiled in a little alcohol, when, on cooling, an increase of the deposit occurred ; No. 3 
yielded decidedly more than No. 1 and No. 2. Having proceeded so far with the experi- 
ment, it was necessary to examine the part of the original deposit insoluble in boiling 
alcohol. The three quantities were boiled separately in a solution of caustic potash till 
they were nearly dissolved, and then an excess of hydrochloric acid was added. There 
occurred immediately an abundant precipitate ; when the fluid had become cold, the 
precipitate was collected on a filter and thoroughly washed 'with water. Each filter 
being diied, fii’st by a temperatm’e not exceeding 55° C., then under the air-pump, over 
sulphuric acid, they were next treated separately with ether until no more was dissolved ; 
by spontaneous evaporation the ethereal solution deposited a crystalline substance*, 
which was washed with water, again collected on a filter, and dissolved in ether; the 
operation being repeated a tim’d time for No. 1, No. 2, and No. 3, the solutions were 
finally evaporated to drjmess, and each residue was dried and weighed: in the three 
cases the substance was colourless, or nearly so. 
The weight of the fatty acid was in 
No. 1 0’047 gramme. 
No. 2 0-056 „ 
No. 3 0-083 „ 
From these experiments I conclude that the amount of margaric acid derived from 
the original deposit varies according to the mode of manipulation, and that the maxi- 
mum quantity is obtained by preparing the alcoholic extract in a glass flask, and strain- 
ing it through muslin ; in which case little of the alcohol is lost by evaporation, and the 
fluid has not time to cool pre-riously to its being strained. 
It is e-vident that the fatty acid contained in the deposit yielded by the alcoholic 
extract of excrements on coohng, did not occur therein as a free substance, for if in the 
free state, it must have been dissolved by the boiling alcohol and ether washings. For 
the purpose of determinmg with which substance it was combined, the acid filtrate from 
the deposit, after it had been decomposed by potash and hydrochloric acid, was sub- 
mitted to a qualitative and quantitative analysis ; the ashes from the burnt deposit were 
also analysed. The inorganic substances present were found to be phosphoric acid and 
lime, and in such a proportion, as will be seen from the result of the quantitative 
analysis, that there was more lime than required to combine with the phosphoric acid, 
the excess of this substance being just in the proportion necessary to convert the 
* 111 that operation the ethereal solution was exposed to the air long enough to ensure the crystallization 
of the whole of the fatty acid. 
