From SrRONTlJN, 37 



and produces an extreme intenfity of heat. By this heat the 

 fpar was rapidly melted, but finking into the pores of the 

 charcoal, it eluded further impreffion. I then had recourfe to 

 the ordinary blowpipe. The fmall mafs readily melted, and 

 on being kept in fufion for fome time, boiled with fo much 

 violence as to fcatter around it minute particles of the liquid 

 matter. After two or three minutes, it was kept fluid with 

 more difficulty ; and, finally, it covered the furface of the 

 charcoal with a thin powdery cruft. Though it ftill effervefced 

 brifkly with muriatic acid, a portion of the fixed air had been 

 feparated ; for a part of it, thrown into dillilled water, impart- 

 ed to it the power of changing to a green violet tell:- papers, 

 and the water acquired a cruft on its furface from expofure to 

 the air. 



10. These experiments, I hope, fatisfa(5lorily fhow, that the 

 native carbonate of barytes can be decompofed by heat alone, 

 and further afford proof of the infufficiency of the theory that 

 has been deduced from the fuppofed impofTibility of accompUfh- 

 ing it. 



11. I HAVE found that barytes is vaflly more foluble in hot 

 than in cold water, and that it is depofited from the former in 

 the ftate of cryftals. To obtain thefe I commonly employ the 

 calcined barytic fpar, and the mode I follow confifts in throw- 

 ing into water, that has juft ceafed to boil, fome pieces of a re* 

 cently burned mafs. The heat that is generated caufes the wa- 

 ter to boil, and I prolong the ebullition for a little time. The 

 clear part of the liquor being decanted off and permitted to 

 cool, depofits fooner or later a quantity of cryftals. 1 he fhape 

 and appearance of thefe vary confiderably, according to the ra- 

 pidity with which they have been formed, and this depends 

 upon the greater or fmaller quantity taken up by the hot wa- 

 ter over what can be retained by it when cold ; the moft fatu- 

 rated yielding cryftals the moft fpeedily, the lefs fo not for feve- 

 ral days. 



12. The 



