134 F. B. GUTHRIE AND C. R. BARKER. 



Weight of anhydrous 



Weight of CaO 



Weight of CaO calcu- 



CaC^O* taken. 



obtained. 



lated from CaC 2 04. 



•0980 



•0428 



•0428 



•0942 



•0410 



•0412 



•1114 



•0486 



•0487 



•0860 



•0376 



•0376 



•0964 



•0420 



•0421 



•0823 



•0360 



•0360 



•0779 



•0340 



•0340 



•2614 



•1140 



•1143 



•2030 



•0888 



•0888 



•1624 



•0708 



•0710 



•3104 



•1358 



•1358 



•3240 



•1416 



•1417 



In the cases where the weight of oxide obtained differs 

 from the weight calculated, the latter weight is always 

 greater than the former, a difference which is undoubtedly 

 to be attributed to the absorption of water by the anhydrous 

 oxalate either during the process of weighing or in the 

 desiccator. 



In all the above determinations the amount of ammonium 

 nitrate used was 0*3 grms, with the exception of the two 

 last (over *3 grms oxalate) in which cases 0*4 grms nitrate 

 was taken. 



W. H. Hess 1 has described a method for the estimation 

 of lime in which a mixture of ammonium nitrate and 

 ammonium sulphate is employed, the lime being converted 

 into sulphate in which form it is weighed, the addition of 

 ammonium nitrate rendering the conversion into sulphate 

 rapid and certain. 



Ignition in a covered crucible with ammonium sulphate 

 alone is recommended by Schrotter, 2 the lime being weighed 

 as sulphate. Presenilis also 3 recommends, after strong 

 ignition of the oxalate, the addition of a little water and 

 solution in HOI. Strong sulphuric acid is then added in 

 excess, evaporated to dryness and ignited. The oxalate is 

 thus converted into sulphate, in which form it is weighed. 



1 Journal of the American Chemical Society, Vol. xxn., (1900) p. 477. 



2 Fresenius Quantitative Analysis, Vol. i., (seventh edition) p. 188. 



3 Loc. cit: 



