158 SMITH— COLUMBIUM AND TANTALUM. |Apnii 3) 



which the analyst has not solved up to the present. As remarked, 

 it has received and is receiving our daily attention. Once having 

 achieved this result and having definitely determined the character 

 of the color-giving metallic acid, or proved it to be titanium, with- 

 out any further doubt, we then hope to subject the purified coiumbic 

 oxide to a searching review in all its derivatives, just as we are now 

 doing with the compounds of tantalum. In anticipation, it may 

 be said that there are some most interesting complexes of tungstic 

 acid with tantalic oxide and also of tungstic acid and coiumbic 

 acid. These are under study at present. These complexes, also, 

 have brought analytical problems that are most puzzling. Yet our 

 progress with them leads us to hope for a separation and a satisfac- 

 tory solution of the same. 



Some attention has likewise been given to per-tantalates and per- 

 columbates. It would not be the least surprising to find these de- 

 rivatives answering admirably for atomic weight work. 



University of Pennsylvania. 



