522 Ohfervaticiis on SirotUiim, 



in powder, and laid the ball on it, I covered it with powdered charcoal, and luted on a 

 cover with common loam. Tilings being thus difpofed, the crucible was kept in a 

 very Itrong fire for a full hour, which time was fullicicnt to difcngage the carbonic acid. 

 The crucible being cold, 1 opened it, and found the little bail pcrfcdiy compacl ; but it 

 now weighed only 70 grains. I then triturated it in a gUfs-mortar with about nine ounces 

 of boiling water, filtrated the litjuor, and, in order to difpofe it the more to cryftallization, 

 put it into a glafs retort, to feparate a portion of the water by diftillation. By cooling, 

 there were formed in the retort cryftals feveral lines in length. 



2. One hundred grains of carbonate of barytes prepared from the fulphate by the ordi- 

 nary procelTes were treated with 10 grains of powdered charcoal, as above dcfcribcd, and 

 the crucible equally expofcd to heat for only an hour. H.iving then treated the refiduc 

 with boiling water, and concentrated the liquor in a retort, 1 obtained, on its cooling, 

 cryftals fimilar to thofe before mentioned. 



3. One hundred grains of carbonate of ftrontian being treated in the fame manner, the 

 rcfidue, after calcination, weighed only 72 grains. Its folution in hot water appeared to 

 pie more faturated than that of barytes ; and, without having recourfe to concentration, I 

 obtained cryftals on its cooling, though I had ufed about the fame quantity of water as in 

 the preceding experiments. I do not, however, believe that ftrontian is much more folublc 

 than barytes ; for in feveral other experiments I have had folutions of barytes fo fully fatu- 

 rated as to cryftallize by cooling confufedly and in a mafs. Thus it is very evident that the 

 a£tion of fire feparates carbonic acid from barytes and ftrontian, and that thefc earths theti 

 become foluble in water, and in larger quantity if boiling, fo as to give cryftals by cooling. 

 This character does not therefore belong exclufively to ftrontian, as M. Klaproth fup- 

 pofes. 



1 have alfo remarked that the aqueous folutions, both of barytes and ftrontian, when 

 pure or calcined, have an odour fomewhat fimilar to that of cauftic pot-afli or foda, or 

 what is commonly called a lisivious odour. 



Habitudes of the Carlcnates of Barytes and Strcntian. 



With nitric acid. NATIVE carbonate of barytes was totally dillblved bydiluted nitric acid, 

 and the folution attended with a difengagement of carbonic acid gas, in the proportion of 

 twenty-two parts in the hundred. The concentrated liquor afforded cryftals, the nioft 

 ordinary figure of which was oftahedral. 



One hundred grains of carbonate of ftrontian were alfo dilTolvcd in nitric acid ; but 

 the difengagement of carbonic acid gas was more confiderable than in the preceding ex- 

 periment, the proportion being thirty hundredths. The fait which rcfults from this com- 

 bination alfo cryftalUzes in o£lahedrons. 



[To be cantintied,] 



PHILO- 



