Gooch and Ward — Copper Oxalate in Analysis. 451 







Table I. 











Effects of 



Concentration in Water Solution. 





Copper 

 taken 



Volume 



at 

 precipi- 

 tation 



Oxalic 

 acid 

 used 



Copper 

 found 



Error 





Average 

 error 



grm. 



cm 3 . 



grm. 



grm. 



grm. 





grm. 





Experiments 



with copper 



sulphate. 







o-oioo 



10 



05 



0-0097 



— 0-0003 



1 





o-oioo 



10 



0-5 



0-0098 



— 0-0002 



y 



0-0002 



0-0502 



10 



0-5 



0-0500 



-0-0002 



j 





0-0502 



50 



2-0 



0-0491 



— 0-0011 



i 





0*0502 



50 



2-0 



0-0491 



—o-ooii 



y 



0-0012 



0-0504 



50 



2-0 



0-0491 



— 0-0013* 



•j 





0-0504 



100 



4-0 



0-0468 



— 0-00361 



1 



y 



J 





0-0502 



100 



4-0 



0-0448 



— 0-0054 



0-0052 



0-0502 



100 



5-0 



0-0449 



— 0-0053 



0-0502 



100 



5-0 



0-0437 



— 0-0065 





0-0506 



200 



10-0 



00303 



— 0-0203 



\ 



0*0203 





Experiments 



B 



with copper 



nitrate. 







0-0455 



10 



0-5 



0-0457 



+ 0-0002 





0-0002 



0*0570 



50 



2-0 



0-056 



— 0-0009 





0-0009 



0-0455 



100 



5 



0-0402 



— 0-0053 



i 



0-0056 



0*0455 



100 



5-0 



0-0395 



— 0-0060 



\ 



* Copper determined electrolytically in 

 f Copper determined electrolytically in 



filtrate = 0-0013 grm. 

 filtrate = 0-0039 grm. 



in the precipitation of the oxalate, at moderate dilution from 

 solutions of the neutral salt, was shown when Peters filtered, 

 without appreciable loss, precipitates from 50 cm3 of hot solu- 

 tion either at once and hot or as soon as the liquid had cooled. 

 The experiments of Table II show in addition that the 

 precipitates, whether thrown down in hot solution or in cold 

 solution, possess after long standing the same degree of insolu- 

 bility. 



Table II. 

 Effects of Temperature at Precipitation and Titration after 



Copper 

 taken 

 grm. 



0-0502 

 0-0502 

 0-0502 

 0-0502 



Volume 

 cm 3 



50 

 50 

 50 

 50 



Standing Over Night. 



Oxalic Copper 



acid found Error 



grm. grm. grm. 



2-0 0-0491 0-0011 



2-0 0*0492 0-0010 



2-0 0-0490 0*0012 



2-0 0-0491 0-0011 



Precipi- 

 tation 



hot 



hot 



cold 



cold 



Filtra- 

 tion 



cold 

 hot 

 hot 

 cold 



