220 Peters — Estimation of Calcium, Strontium and 



0-0974 



SrO, Volume Acid 



taken as Ammonium at present SrO 



Sr(N0 3 ) 2 . oxalate. precipitation. during found. Error. 



grm. grm. cm 3 . titration. grm. grm. 



0-0487 0-064 100 H 2 S0 4 0-0441 — 0'0046 



" 0-0768 " " 00465 —0*0022 



0-16 " " 0-0488 —0-0001 



0-128 " " 0-0939 —0-0025 



0-16 " " 0-0959 —0-0015 



" 0-32 " " 0-0975 f 0-0001 



The solvent action of a large amount of water on a precipi- 

 tate of strontium oxalate was tested by washing a precipitate 

 equivalent to 0*0974 grm. of the oxide with 150 cm3 of cold 

 water. The precipitate, when weighed as the sulphate, showed 

 a loss of 0-0033 grm. as the oxide, which amount was subse- 

 quently recovered from the filtrate by the addition of ammo- 

 nium oxalate and alcohol. Plainly excessive washing with 

 water is to be avoided. In the estimation, therefore, of stron- 

 tium when precipitated as the oxalate in water solution the 

 amount of water used in washing was limited. It was found that 

 30-40 cm3 of water judiciously applied was sufficient to wash out 

 the ammonium salt without producing appreciable solvent 

 effect upon the strontium oxalate. 



The process of treatment was similar to that used in the 

 precipitations from alcoholic solution, excepting that no alco- 

 hol was added to the solution, that the washing was effected 

 with a limited amount of water, and that, there being no alcohol 

 present to affect the titration, the precipitate was not dried 

 before treatment with permanganate. The results are given in 

 Table YI. 



Table VI. 



SrO, 





Volume 



Acid 







taken as 



Ammonium 



at 



present 



SrO 





Sr(NO a ) a . 



oxalate. 



precipitation. 



during 



found. 



Error. 



grm. 



grm. 



cm 3 . 



A • 

 100 



titration. 



grm. 



grm. 



0-0974 



0-5 



H,S0 4 



0-0966 



— 0-0008 



u 



a 



a 



a 



0-0985 



+ 0-0011 



a 



a 



cc 



a 



0-0977 



+ 0-0003 



a 



a 



u 



a 



0-0963 



—o-ooii 



a 



0-8 



u 



a 



0-0981 



+ 0-0007 



a 



n 



t( 



ic 



0-0966 



— 00008 



a 



1-0 



n 



a 



0-0965 



— 0009 



a 



2-0 



a 



a 



0-0963 



-o-ooii 



a 



a 



u 



a 



0-0970 



— 0-0004 



0-0778 



0-5 



u 



a 



0-0792 



+ 0-0014 



a 



a 



a 



a 



0-0767 



-00011 



a 



a 



ii 



a 



0-0776 



— 0-0002 



a 



a 



k 



a 



0-0776 



— 0-0002 



0-0974 



0-8 



250 



a 



0-0973 



+ 0-0001 



a 



2-0 



u 



a 



00975 



—o-oooi 



