Objervat'ions tn Stnntian, j^f 



AhJiraB of Two Memoirs on a New Method of ohtaimng Barnes pure., and oil the Properties of 

 this Earth compared with thofe of St rout tan. By Citizens FoURCROY and VaU^UELIN, 

 Reed t» the National hijiittitey Jl^th April and ZlJ} September 1 796*. 



X HE difficulty of obtaining barytes pure, and the almoft total jmpoffibility of feparating 

 this earth from the carbonic acid by calcination of its carbonate, are already fufficiently 

 known. In a courfe of Experiments undertaken jointly by Citizens Fourcroy and 

 Vauquelin, to determine the charafters and diftinflive properties of the falts and com- 

 pounds formed by barytes, one of the points which they were mofl defirous of attaining, 

 was of courfe to obtain this earth in a real flate of purity. Citizen Vauquelin having at 

 length difcovered a means of efFe£ling this purpofe by the decompofition of nitrate of ba- 

 rytes by the adlion of fire, it became more eafy to thofe chemifts to examine fuch pro- 

 perties of this earth as had hitherto been unknown to them. The two memoirs of which 

 we are here about to give an abftraft, fliow the mofl remarkable properties which charac- 

 terize both this earth and flrontian. 



1. Nitrate of barytes in o£lahedral cryftals, being expofed to the aflion of fire in a por- 

 celain retort, melts, fwells, and gives out much oxygenous and azotic gTls, with fcarcely 

 any nitrous vapour ; and the retort being fuffered to cool when no more elaflic fluid is dif- 

 engaged, there is found on breaking it a grey, folid, but fomewhat porous, mafs of a harfh • 

 tafle, and more cauftic than quick-lime, which is pure barytes. 



2. Expofed to the blow-pipe on a piece of charcoal, this earth fufes, bubbles up, and runs ■ 

 into globules which quickly penetrate into the charcoal. 



3. In the air it efBorefces, cracks, burfts, fwells up, heats and whitens, and, becoming thus 

 rapidly flaked, it abforbs 0.22 of its weight of water and carbonic acid. 



4. It abforbs water with extreme avidity, melts with hiffing, heats confiderably, folidifies 

 the water, and cryftallizes and hardens with it in I'uch a manner as to become a very tena- 

 cious cement, capable of adhering very flrongly to glafs. A little more v/ater changes it 

 into a very bulky white powder. If it be entirely covered with water, it diflblves in it with 

 a violent^hiffing, and then cryftallizes in tranfparent needles, which adhere together, and 

 form compages like the particles of beaten plafter. 



5. Cold water diflblves a twenty-fifth part of its weight \ boiling water more than half: 

 the latter by cooling depofits very beautiful tranfparent prifms, which cfflorefce and become 

 pulverulent when expofed to the air. 



6. A folution of barytes has its furface more readily incrufted with a pellicle by expofure 

 to the air, and depofits a more abundant precipitate by carbonic acid than Hme-water. 



7. The oxalic, citric, phofphoric, and phofphorous acids precipitate this folution and 

 the precipitates are re-diflblvcd by the addition of an excefs of the acids by which they arc 

 formed. 



8. This folution decompofes thofe of fbap, and of the nitrates of mercury, lead, and 



;* Tianflatcd from Annalcs de Chimic, XXI. p. 276, by J. F r. 



CIver, 



