[ 2o6 ] 



Baroselenite or Vitriolated Barytes. 



Barytic Solutions being the mofl delicate teft of vitriolic acid 

 as yet known, the determination of the proportion of real vitriolic 

 acid taken up in the artificial compound of both is of the greateft 

 importance, and its agreement v^'ith the foregoing determinations 

 will tend to their mutual eftablifhment. 



I HAVE already mentioned that by real vitriolic acid I mean acid 

 of fuch ftrength or concentration as exifts in well-dried and neu- 

 tralized vitriolated tartarin. If therefore I can fliew in what pro- 

 portion the acid contained in a given weight of this fait enters 

 into the compofition of a given weight of thoroughly dried barofe- 

 lenite, the proportion of real acid in this laft will of courfe be de- 

 monftrated. Now this may very nearly be afcertained by the ex- 

 periment of Dr. Withering, Phil. Tranf. 1784, p. 304. But firft 

 I muft premife that by the experiments of the moft accurate ana- 

 lyfts, 100 parts barofelenite when fufiiciently dried contain very 

 nearly 33 of vitriolic acid. 



The refults obtained by Dr. Withering were as follow : 



I ft. 480 grains of barofelenite being fufed with 960 of fait of 

 tartar, 428 grains of the barofelenite were decompofed, Bnd 52 

 remained undecompofed. 



2dly. 



