Of WHINSTONE and LAVA. 85 



1. It was not volatile in a moderate red heat. 



2. After being thus dried, it diffolved readily in about fix times 

 its weight of water, at the temperature of 60 of Fahrenheit. 



3. This folution gave, by evaporation, cryftals exadly the 

 fame in form as artificial fulphate of foda ; and thefe cryftals 

 efflorefced in dry air. 



4. A PART of the folution of this fait being boiled with car- 

 bonate of foda, gave no precipitate ; a proof that it contained 

 no earthy matter. 



5. Some of the folution being mixed with a very ftrong fo- 

 lution of acid of tartar, remained unafFefled ; the fait therefore 

 contained no potafh. 



6. Some of the fait being diffolved in water, was decompofed 

 by nitrate of barytes ; and the fulphate of barytes produced was 

 feparated by filtration. The nitric acid, thus united to the al- 

 kaline bafis, formed a faline compound, which, in the next place, 

 was mixed and deflagrated with charcoal. By wafhing the 

 coaly refiduum, and evaporating the water, I obtained pure car- 

 bonate of foda, which efflorefced readily in the air. 



There can be no fufpicion of the retort which was ufed fur- 

 nilhing any part of the alkali ; for I weighed it previoufly in a 

 balance of great accuracy ; and after the operation was finifhed, 

 found its weight exactly the fame as at firft, and the luftre of 

 the glafs altogether unimpaired. 



The whin which I next fubmitted to examination, for the 

 purpofe of feparating the foda, was taken from a quarry near 

 the Water of Leith *. I ufed a confiderable quantity, 800 grains ; 

 which were diftilled twice with fulphuric acid, and then treated 

 in every refpedl exadly as the preceding. The fulphate of foda 

 obtained, amounted to 43 grains. 



i 



• This fpecies is the firft mentioned in Sir James Hall's paper. When pow- 

 dered, it effervefced flightly with acids. I did not analyze it ; but, in the courfe of the 

 procefe for detefting foda, one of the earthy precipates proved, upon examination, to 

 be magnefia. It is the only whin in which I have found this earth. 



