[ 239 ] 



!' termed, abfolntely real acid. One hundred parts bf calcined- 

 fulphate of lime contain therefore. 



Lime - . . ej 



Sulphuric acid - -- - 43 



100 



By the former experiments (thofe made upon fulphur con- 

 verted into acid, and then united to Barytes) we had the- quan- 

 tity of fulphur, contained in fulphate of Barytes. By the latter 

 (thofe. made by diredly combining lime with fulphuric acid) 

 we had the proportion of real acid, contained in calcined ful- 

 phate of lime. Confequently, by knowing the ratio, that ful- 

 phate of Barytes bears to fulphate of lime, with regard to the 

 acid in each,, we fhall arrive at the knowledge, of the quantity 

 of fulphur, contained in. real fulphuric acid. For this purpofe, 

 I attempted to difTolve, in water, 100 parts of fulphate of lime. 

 But finding, in this method of proceeding, a confiderable incon- 

 venience arrfing from the great quantity of liquor, necefTary to 

 effed the folution of that fak, I had recourfe to the following 

 expedient. Upon loO: grains of calcined fulphate of lime, I 

 poured fome oxalic acid,. which attradts the bafis with an affi- 

 nity fuperior to that exercifed by fulphuric acid. Oxalate of 

 lime was here, formed; but oxalate of lime is foluble in a very 

 fmall excefs of any acid. A little muriatic acid operated a com- 



Gg3 pletc- 



