*B8 CHEMICAL ANALTSIS 



fiance *. He has not mentioned the circumftance in any of his 

 works; but Dr Black has been accuftomed, as he informed me 

 himfelf, to take notice of it in his lectures on chemiftry, for 

 many years. It is my intention to analyze fome fpecies of zeo- 

 lite ; and if the refults feem of any importance, they mall be 

 laid before the Society. 



Among the experiments on the bafalt of StafFa, already de- 

 fcribed, it has been obferved, that, when the powder was boil- 

 ed in water, a flight precipitate was produced in the water by 

 nitrate of filver, thus indicating fome traces of muriatic acid. 

 As it appeared of importance to determine how much of this 

 acid the bafalt contained, I fubjected fome of it to examination 

 for that purpofe. 



Experiments to a/certain the Quantity of Muriatic Acid in the Ba- 

 falt ofStaffa. 



One hundred grains of the ftone, in fine powder, were mix- 

 ed in a fmall retort with fome nitric acid ; and a receiver being 

 adapted, the mixture was boiled gently, till the greater part of 

 the acid had dillilled over. The liquor in the receiver being 

 examined with nitrate of barytes, remained unaffected j but 

 gave a flight cloud with nitrate of filver, which fhewed that it 

 contained fome muriatic acid. 



The mafs in the retort being diluted with water, the whole 

 was filtered ; and this filtered liquor produced no cloud with 

 nitrate of barytes, but gave, like the former, a flight precipitate 

 with nitrate of filver. 



In 



* In the 26th volume of the Annates de Chimie, p. 119. M. Scherer, in a letter 

 to Van Mons, fays, that he was informed by Dr Black, that Dr Hctton had, 

 long ago, found potajh in zeolite. In this ftatement M. Scherer is incorreft j be- 

 -aufe it was foda, as above mentioned, which Dr Hutton obtained from that fubftance. 



