414 -^ Chemical Analyfii of Three Species of Whinjlone, and Two of Lava. 



It is well known among the friends of the late Dr. Hutton, that he made feme experi- 

 ments on zeolite; by which he concluded, that foda entered into the compofition of that 

 fubftance *. 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 lecSlures on 

 chemiftry, for many years. It is my intention to analyze fome fpecies of zeolite ; and if 

 the rcfults feem of any importance, they (hall be laid before the Society. 



Among the experiments on the bafalt of StafTa^ already defcribed, it has been obferved, 

 that, wlien the powder was boiled 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 im- 

 portance to determine how much of this acid the bafalt contained, I fubjefted fome of it to 

 examination for that purpofe. 



Experiments to afccrtain the ^latitity of Muriatic Acid in the Bafalt of St off a. 



One hundred grains of the ftone, in fine powder, were mixed 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 diflilled over. The liquor in the receiver being examined with 

 nitrate of barytes, remained unaffedted; but gave a flight cloud with nitrate of filver, 

 which Ihewed that it contained fome muriatic acid. 



The mafsin 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 pre- 

 cipitate with nitrate of filver. 



In the next place, the undifTolved refiduum was mixed with twice its weight of very pure 

 cauflic pot-afh, and expofed to a low red heat, for an hour, in a filver crucible. The 

 mafs was then diluted with water, fuperfaturated flightly with nitric acid, and filtered. 

 With this folution nitrate of barytes produced no tSeO. ; confequently, thefe experiments 

 {how, that the ftone in queftion does not contain any traces of fulphuric acid. With 

 nitrate of filver, however, the folution gave a white precipitate, more abundant than the 

 two preceding. The different portions of muriate of filver, being coUedled, and dried on 

 a fand bath, weighed only 4 grains. 



As a fourth part of muriate of filver conCfts of acid, according to the moft corre£l 

 experiments hitherto publifhed, thefe 4 grains confequently Indicate, in 100 parts of this 

 bafalt, only about one of muriatic acid. All the whins and lavas, to be mentioned in 

 the remaining part of this paper, were found, by a fimilar procefs, to contain about 

 the fame quantity. 



* In the iSth volume of the Annales de Cbimli, p. 119. M. Scherer, in a letter to Van Mens, fays, that 

 )ie was informed by Dr. Black, that Dr. Hutton had, long ago, found pot-a/h in zeolite. In this itate- 

 ment M. Scherer is inconeft, becaufe it was foda, as above-mentioned, which Dr. Hutton obtained fr»ni 

 that fubftance. 



3 According 



