Bayley — Oh Complex Oxides of Cohatt and Nickel. 101 



'XVII. Ojf THE FoElSIATIOIv" A^D COMPOSITION OF SOME CoMPIEX OxiDES 



OF CoBAXT AND jS'ickel. By Thomas Batlet, Associate Boyal 

 College of Science, Ireland. 



[Read, June 25, 1877.] 



"While preparing standard solutions of nickel and cobalt salts for the 

 purposes of a research on the colorimetric relations and on the colori- 

 metric estimation of those metals, I was endeavouring to use a modifi- 

 cation of the method of estimating nickel and cobalt, indicated by 

 Bunsen^ depending for their determination on the iodine liberated by 

 the higher oxides of these metals in contact with hydrochloric acid, 

 and potassium iodide. The method was as follows : — The solution of 

 the nickel or cobalt salt was made alkaline by soda and then mixed 

 with excess of sodic hypochlorite obtained by the action of cold 

 •dilute sodic carbonate on fresh bleaching powder. 



After allowing the slightly warm solution of nickel or cobalt to 

 stand some time, so as to ensui'e complete oxidation, the temperature 

 was raised until brisk effervescence ensued, and the solution allowed 

 to remain at that temperature until the excess of hypochlorite was 

 decomposed. "When the evolution of oxygen had ceased, the liquid 

 was boiled for about half an hour. I found that by tliis process it is 

 easy to destroy all matter, except the oxide, capable of liberating 

 iodine on treatment with potassic iodide and hydrochloric acid. The 

 solution having been cooled, it was mixed with excess of potassic 

 iodide, and then with enough hydrochloric acid to dissolve the 

 suspended oxide. The liberated iodine was then estimated by a 

 standard sokition of sodic thiosulphate (IS'as So O3). 



In the first experiments I used a standard solution of nitrate 

 of nickel, and calculated the nickel from the iodine set free according 

 to the following equation : — 



Ni. O3 + 6HC1 = 2M CI2 + CI2 + 3H3O. 



The results were not satisfactory, as will be seen from the following 

 Table :— 



Nickel used. 



Mckel found 



grams. 



grams. 



•1570 



•1437 



•1570 



•1580 



•1570 



•1465 



•1570 



•1568 



•1570 



•1639 



•1570 



•1541 



1 Ann. Ch. Pharm. Ixxx\a. 265. 



