278 FIXED ALKALIES AND ALKALINE EARTHS. 



treatment reduced to 7 grains of chloride of cal- 

 cium. I shall relate one experiment to show the 

 reader how near to these numerical results I 

 have been able to come. 12*5 grains of pure 

 calcareous spar (containing 7 grains of lime) 

 were dissolved in muriatic acid, in a plati- 

 num crucible, the weight of which had been 

 previously determined. The solution was slowly 

 evaporated to dry ness, and the dry salt was 

 fused by exposing the salt to a red heat. The 

 fused salt was white and opaque, and weighed 

 13*98 grains, as nearly as could be determined. 

 Water being poured upon it, there remained 

 undissolved 0*1 7 grain of a white powder con- 

 sisting chiefly of carbonate of lime ; but contain- 

 ing also one or two flocks of sulphate of lime, 

 apparently derived from a trace of sulphuric 

 acid, in the muriatic acid employed to dissolve 

 the calcareous spar. Now, 0*17 carbonate of 

 lime contain 0*09-5 lime = 0-0678 calcium, which 

 requires for saturation 0*122 chlorine, making 

 together 0*1898 chloride of calcium ; which ex- 

 ceeds the 0*17 grain of carbonate of lime by very 

 nearly 0*02 grain ; making (as near as I could 

 determine) almost exactly 14 grains. 



Now, these 14 grains contained 2 atoms chlo- 

 rine = 9, and 2 atoms calcium, which must 

 amount to 5. So that the atomic weight of cal- 

 cium is obviously 2*5 ; and lime is a compound 

 of 1 atom oxygen and 1 atom calcium. 



