12 STUCCO FOR PRESERVING STOKE. 



wet sponge, be observed, that the oystersbell powder was 

 taken at random, and added to ,the cheese till it had ac- 

 quired the cotisistency of a paste capable of being spread on 

 p«per. 

 Oxideof leid "^^^^ committee having obtained from Mr. Bachelier a 

 »iti. few leaves of paper covered with thin paste, found from the 



tery deep black immediately given it by the hidrosulpburet 

 of potash, that it contained a considerable quantity of oxide 

 of lead, the presence of which there was no reason to sus- 

 pect in the preservative stucco, so that they could not be 

 considered as the same. 

 Ar-i? sisofthe ^* remained therefore to analyse the stucco, which wap 

 !&i4JUiix done by Mr. Vauquelin; though, as a very small quantity 



only could be obtained by scraping the pillars, it did not 

 admit of repeated trials. The results of his analysis gave 



Carbouate of lime • • • 63 



Sulphate of lime •• 7'73 



Carbonate of lead 6 



Oxide of iron, about 4 



Siit'x <• 2 



Water • 20 



Organic matter, an indeterminate quantity 



102-73 



The surplus of 2*73 Mr. Vauquelin ascribes either to the 



matter not having been dried to the same degree, or to the 



escape of a little carbonic acid during the calcination. 



Nom»mal ■ The presence of animal matter was sought for, but not 



f"^?' *"'*""<'» a particle could be separated. The smell it emitted during 



t'u: the pun- r r o 



K«is? njc» of calcination no way resembled that of aminal matters; on 

 ** h^T" T^t^ ^^ contrary it had the pungent sharpness of vegetable 

 siibstances. On being exposed to the action of heat in a' 

 retort however, a clear and almost colourless liquid came 

 over, from which potash expelled a very evident amraonica' 

 In«iJc3tiorisof \^ipcnr. This indicates, that some animal substance en- 

 amuia mat. jp^.pjj i,ito the composition, but that in time it was decom- 

 posed, and left only an ammonical salt. The brownisl 

 colour it acquired in the fire also proves, that some anima 

 waiter still remained in it; though altered in its nature 

 since it neither emitted the smell proper to such substances 

 jifpr yielded any preceptable quantity of oil, i-astl^ 



