Analyjis of the Mellite ar Honigjlein. 517 



m. 



This 0.8 of a gramme of brown matter calcined in a crucible became white, and then 

 weighed only 0.33 gramme. When mixed with diluted fulphuric acid, it produced a 

 flight effervefcence. The mixture was afterwards evaporated to dr jrnefs. 



I expeded from the information of Mn Klaproth, that by the addition of water, nearly 

 the whole of this matter would have been diflblved ; but die contrary happened, for the 

 greateft part remained in the form of a white powder. 



The fluid being evaporated to the point, at which there remained at mod not more than 

 three or four grammes, L added one drop of fulphate of pot-afli, and obtained, by leaving 

 it to fpontaneous evaporation, about 0.1 gramme of alum, mixed with a fmall quantity of 

 fulphate of lime. 



I afterwards examined what might be the nature of the fubftance, which after the treat- 

 ment with fulphuric acid remained infoluble in water. 



For this purpofe I boiled it in a folution of carbonate of pot-afli j then filtered,, waflied^ 

 and examined it as follows : 



I.. The muriatic acid, diluted with two parts of water, attacked it with a flight effer- 

 vefcence } but the folution did not become clear ; on the contrary it remained fomewhat 

 milky. 



2. This filtered liquor afforded with ammonia a precipitate refembling in its tranfpa- 

 rency that which alumine affords by the fame means ; but it was not entirely foluble ia 

 pot-a(h. 



But the portion diffolved by the pot-afh was the mod abundant, and prefented all the 

 charaders of alumine : for when combined with the fulphuric acid it afforded alum. The 

 caufe why this portion did not remain combined with the fulphuric acid was therefore,, 

 moft probably, that it had been too much heated towards the end of the deficcation. 



The fluid from which the ammonia had feparated the alumine laft mentioned, afforded 

 alfo flight precipitates by the carbonate of pot-afh, and the oxalate of ammonia ; which 

 proves that it contained a fmall portion of lime. 



The portion of matter which was not diffolved by the pot-afh, weighed at moft o.i 

 gramme, and appeared to me to be filex. 



The honigftein therefore contains a fmall portion of lime and of filex. 



After having afcertained the matter which compofed my refidue, I direfted my opera- 

 tions to the liquid which muft have contained the acid of mellite combined with pot-afh j; 

 and with the expe£lation that it would yield its bafis to the mineral acids, I added to a 

 portion of the liquid fome drops of nitric acid, which produced a very flight effervefcence^ 

 and difengaged a very fmall portion of brown flbcculent matter. Some hours afterwards,, 

 that which I fufpefted came to pafs ; the acid of the mellite cry ftallized in the f&rm of 

 fmall ihort prifms with brilliant faces.. 



3: Finding 



