ON THE YOLK OF WOOL. , Q^ 



tains feme portions of fat matter, which, by decompofing the 

 fulphate of lime, and forming a little fulphuret would facilitate 

 the fufion. I regret my not having had a fufficient quantity of 

 this fait, to examine its properties more minutely. 



The yolk diffolved in water, filtered, and infpiflated, having Acetic add; 

 been diftilled with dilute fulphuric acid, furniflied a liquor in 

 which I eafily recognized acetic acid, by its odour, its tafte, 

 and the properties of the faits which it formed with different 

 bafes, particularly with lime and potalh. 



Thus the yolk contains acetic acid, which without doubt is 

 combined with part of thepotafli. 



It alfo contains muriate of potafli, for, with the folutlon of and muriatic 

 filver it forms an abundant precipitate,, which is not entirely ^'^^^' 

 foluble in nitric acid; and, by diftillation with fulphuric acid, 

 it gives fenfible indications of muriatic acid, which is mixed 

 with the acetic acid. 



The yolk evaporated to drynefs, and ftrongly heated in a 

 filver crucible, fwells, chars, and exhales fetid ammoniacal 

 vapours ; afterwards oily fumes arife which take fire, and 

 when the greatefl part of the oil is diffipated, it reddens, and 

 enters into quiet fufion^ If, at this moment, it be poured on a 

 marble, it yields a fubftance which contracts by cooling, of a 

 greyilh colour, and a very cauftic alkaline tafte : if this fub- 

 ftance be afterwards diffolved in water, there only remains an 

 infinitely fmall quantity of carbonaceous matter, and, by eva- 

 poration, the liquor yields a true potaOi flightly carbonated. 



It refults from thefe experiments that the oil or greafe, Recapitulation 

 whofe prefence in the yolk has been demonftrated by means °^ ^^^ "'"P"' 

 of the acids, is combined in it with potafli, in the flate of a true 

 animal foap ; that, befides, there is a portion of carbonate of 

 potafli in excefs, fince the acids produce a pretty brilk frothy 

 effervefcence in the concentrated folution of the yolk. In ad- 

 dition to the fubftances wliich I have jufi mentioned, the yolk 

 contains a certain quantity of animal matter ; for, by diftilla- 

 tion, it gives very fenfible traces of ammoniac, and an oil 

 whofe fetid odour refembles thofe furniflied by animal matters. 



The yolk is therefore formed, ]Ji, Of a foap with a bafe of 

 potafli, which makes the greateft part; 2d, Of a fmall quan- 

 tity of carbonate of potafli ; 3d, Of a perceptible quantity of 

 acetate of potafli ; 4:th, Of lipie, whofe ftate of combination 



I am. 



