Manchester Memoirs, Vol. xlvii. (1903), No. \%. 9 



cipitated oxide, — whether it must be represented as 

 C07O1, or C00O14, so for the purpose of this analytical 

 method 1 have taken the mean of the two (which would 

 correspond to an oxide C016O25) and, in calculating the 

 amount of cobalt present, it may be taken that each cubic 

 centimetre of the decinormal thiosulphate corresponds to 

 ■005244 of metallic cobalt, or to -0066 of the monoxide, 

 CoO. 



Mr. J. H. Davidson, B.Sc. (Vict.), chemist at the 

 Goldenhill Cobalt, Colour and Chemical Works, Stafford- 

 shire, has been good enough to test this volumetric process 

 in the assay of some of the cobalt ores which he has to 

 deal with, and I have to thank him for kindly giving me 

 permission to append his results. 



The four samples (see following Table) were New 

 Caledonian ores. Column A gives the result by Mr. David- 

 son's usual method (Clarke's Phosphate process) ; column 

 B gives the check assays by the analyst for the brokers, 

 and column C gives the results by my proposed volu- 

 metric method. The results are all in percentages of 

 cobalt monoxide, CoO. 



Mr. Davidson has also performed three separate assays 

 of a specimen of speiss by three different methods. In 

 method A the cobalt was separated as phosphate and 



