ON THE YOLK OF WOOL. £) 1 



3d. In time it gives a depofition of fand, carbonate of lime, 

 and feveral other foreign bodies; it lathers by agitation and 

 heat like a foliition of foap. 



4th. The water with which wool has been waQied, filtered Aq"<:ous folu- 

 1 , . ,, . ^ , ■ , 1-, r ,. tion and extradl. 



and evaporated, yields a brown extrad, thick like a lyrup, ot 



an acrid, fait, and bitter tafle: in this Aate it ftill retains its 

 peculiar odour. 



5th. Alcohol, applied to this extrad, didolves a part which Extraft expofed 

 communicates a reddifli-brown colour to it: if the alcohol be ^° ^'^^ ° • 

 feparated from this fub (lance by evaporation, it affiimes the 

 form of a tranfparent, thick, and vifcous honey. 



Xhe following are fome of the properties which it offered : To acids. 



Ifl. It diflblves eafily in water, and its folution is fpeedily 

 coagulated by the acids, which feparate a fat fubftance from it, 

 infokible in water. The matter thus feparated by the acids, 

 collects very flowly; its colour is yellowifli. The acids, as 

 \yill be feen lower, retain a great quantity of it in folution, 

 which gives them a reddifli brown colour. By evaporation. It yields falts 

 the greateft part of this fubflance, diflblved by the acids, 's ]|^g^^Y ,otafli • 

 <iepofited in the form of a black bitumen, and falts are obtained 

 with bafe of potadi and of lime. The greafy matter is fo ad- 

 herent to thcfe falls that. they cannot be obtained in a flate of 

 purity and whitenefs, until after feveral calcinations and folu- 

 tions. 



At the fame time that the acids precipitate this fat matter, Acetous aciJ, 

 they drive off a certain quantity of acetous acid, very dif- acid, 

 tinguifliable by its odour. Concentrated fulphuricacid black- 

 ens the infpiffated yolk, and difengages fome vapours of mu- 

 riatic acid, 



2d. Lime-water renders the folution of tiie yolk turbid and I'ime-water. 

 milky, but it does not form a coagulum in it as in a folution of 

 common foap. 



3d. Cauftic alkalis or quick'lime do not demonftrate the Cauftic aikalis 

 prefence of ammonia. '""^ quick- lime. 



4th. Nitrate of filver produces a yellow precipitate in it. Nitrate of filver. 

 which attaches itfelf to the fides of the veffel, like a fat fub- 

 fiance. Great part of this precipitate is diffolved in nitric acid. 



The part of the yolk which is infoluble in alcohol has fiill a Theinfoluble 



fait tafle, but lefs diftinft than the part which is foluble in this 



re-agent. After having been thus treated with alcohol, it does Is not entirely 



not entirely re-diffolve in water: there remains a glutinous r" J'""'^'" 

 ■ ■' ' . . o aitcr havingbeen 



matter, treated with 



alcohol. 



