456 Gooch and Ward — Copper Oxalate in Analyi 



of copper oxalate. Of these details an account is given below, 

 in Table VI. 



The supersaturated solution (A) was frozen and the mass 

 melted, following procedure which has been found to be success- 

 ful in hastening the deposition of small amounts of ammonium 

 magnesium arsenate :* the supersaturated solution (B) was 

 evaporated to dryness, and the residue extracted with water : 

 alcohol was added (C) to the solution of the copper salt before 

 attempting precipitation by oxalic acid : acetic acid of 50 per 

 cent strength (D) was used as the medium in which precipita- 

 tion was attempted by oxalic acid. 



Table VI. 



The Precipitation of Small Amounts of Copper. 



Volume Alcohol 



at pre- 



Copper 

 taken 



of 

 liquid 



Oxalic i 

 acid ci] 



grm. 



cm 3 . 



grm. 





The effect 



o-ooio 



50 



1-0 



0-0020 



50 



1-0 



0-0030 



50 



1-0 



0-0040 



50 



1-0 



0-0050 



50 



1-0 



o-oioo 



50 



1-0 



0-0200 



50 



1-0 



0-0502 



50 



1-0 



The effect 



of evaporation 



o-ooio 



50 



1-0 



00020 



50 



1-0 



0-0030 



50 



1-0 



0-0040 



50 



l-o 



o-oioo 



50 



P0 



0-0200 



50 



1-0 



0-0502 



50 



1-0 





The effect of 



o-ooio 



50 



2-0 



0-0020 



50 



20 



0-0030 



50 



2-0 



0-0040 



50 



2-0 



0-0050 



50 



2-0 



o-oioo 



50 



2-0 



0-0200 



50 



2-0 



0-0502 



50 



2-0 





* Gooch and 



Acetic 

 acid at 

 precipi- 

 tation 

 cm 3 . 



Nitric 

 acid at 

 precipi- 

 tation 

 cm 3 . 



Copper 



found 



grm. 



Error 

 grm. 



The effect of freezing, melting and boiling. 

 none 



to dryness and extraction of the 

 5Qcms f wa ter. 



0-0005 



— 0-0015 



0-0024 



— 0-0006 



0-0030 



—o-ooio 



0-0039 



— 0-0011 



0-0088 



-0-0012 



0-0188 



— 0-0012 



0-0490 



— 0-0012 



i of the residue with 



0-0004 



— 0-0006 



0-0018 



— 0-0002 



0-0027 



— 0-0003 



0-0036 



— 0-0004 



0-0095 



— 0-0005 



0-0196 



— 0-0004 



0-0499 



— 0-0005 



c 



precipitation in 50 per cent alcohol. 



25 none 



25 none 



25 0-0015 



25 0-0020 



25 0-0016 



25 _,_ . 0-0085 



25 0-0198 



25 0-0499 



Phelps, this Journal, xxii, 488, 1906. 



— 0-0015 

 -0-0020 



— 0-0034 



— 0-0015 



— 0-0002 



— 0-0003 



