ACCOUNT OF A MINERAL SUBSTANCE. 137 



about one-fourth of the powder was diflblved ; and the re- 

 mainder, which appeared little if at all altered, fubfided to 

 the bottom of the vefTel. 



The clear folution, which contained a great excefs of alkali, affords a fcaly 

 was decanted; and, by gentle evaporation, vielded a white ghttcnng falt > 

 glittering fait, in fcales, very much refembling the concrete 

 boracic acid, 



The fait was placed upon a filter, fo that the lixivium might permanent ia 

 be feparated. It was then warned with a fmall quantity of the air > 

 cold diftilled water; and, being dried, remained as above 

 defcribed, although conftantly expofed to the open air. 



This fait had an acrid difagreeable flavour, and contained a acrid tafle : fo- 

 fmall excefs of alkali. It did not diffolve very readily in cold luble in water '> 

 water ; but, when diflblved, the folution was perfecl and per- 

 manent. 



Some nitric acid was added to part of the folution, and im- precjpitable by 

 mediately rendered it white and turbid. In a thort time, a mi 

 white precipitate was collected, fimilar to that which had 

 been employed to neutralife the potalli : and the clear fuper- 

 natant liquor, being evaporated, only afforded nitre. 



Pruffiate of potafh was added to another portion; but did Pruffiate of pot- 

 not produce any effecl, until fome muriatic acid was dropped .. gave n< ? P re " 



. v . . 1-1 . cipitatc unlets 



into the liquor, which then immediately aflumed a tinge of acid was added j 



olive green, and ilowly depofited a precipitate of the fame 



colour. 



Tincture of galls did not affect the folution at firft ; but, nor did galls. 

 , when a few drops of muriatic acid had been added, it gra- 

 dually loft its tranfparency, and yielded an orange-coloured 

 precipitate. 



2. As fo large a part of the white precipitate had remained The portion not 

 nndiflblved in the foregoing experiment, it was digefted again d jjp lved in PJ e - 

 with another portion of the fame lixivium, but without any luble till after 

 effect. I therefore wafhed off the alkali, and boiled fome treatment with 

 nitric acid with the powder, until the acid was completely 

 evaporated. After this, the powder was expofed to a ftrong 

 heat in a fand-bath. It was then again digefted with the It left a refidue 



lixivium, and a part was diflblved as before; but ftill the re- having . the famc 



... properties, 



fiduum required to be treated with nitric acid, before the al- 

 kaline liquor could again ad upon it ; fo that it was necefTary 

 to repeat thefe alternate operations feveral times, before the 

 whole of the powder could be united with the alkali. 



3. When 



