1896.] N. C. l^ag— Notes 07i New Salts of Cobalt and Nickel .HO 



cobalt carbonate precipitated with potassium bicarbonate, and then to 

 add to it a solution of potassium bicarbonate in excess and afterwards 

 bromine; there is a rapid effervescence of carbon dioxide, while the 

 pink precipitate of cobalt carbonate gradually goes into a solution of 

 green colour. That the new compound is not a compound of bromine 

 is seen from the fact that when a concentrated solution is shaken with 

 alcohol and ether, the new compound, with excess of potassium bicarbo- 

 nate settles down immediately and adheres to the bottom of the vessel , 

 while the colourless solution with the whole of the bromine in the state 

 of bromide, &c., can be poured off, leaving the new compound with the 

 excess of potassium bicarbonate free from bromine compounds. But 

 after this extraction with alcohol, the substance is liable to decomposi- 

 tion even in watery solution, probably due to the presence of adherino- 

 alcohol. Use of filter papers with the substance is also not at all safe ; 

 both of which facts point to the compound being of a highly oxidising 

 nature, and easily decomposable by organic substances. All attempts to 

 isolate the substance have hitherto failed. 



The compound seems to be an oxidation product correspondino-,. 

 possibly, to the ferrates. If the aqueous solution of the new compound 

 with the excess of potassium bicarbonate after extraction with alcohol 

 and ether be left for some time, tiie solution as it becomes reduced exlii- 

 bits dichroism, due probably, to the presence of a violet coloured precipi- 

 tate which comes down. The green solution when treated with yellow- 

 ammonium sulphide or sulphuretted hydrogen, first gives a dark brown 

 solution, probably going to a lower oxidation product, and then becomes 

 further reduced and precipitated. Solution of ammonia, too, reduces the 

 substance, discharging the green colour, and giving probably cobalt- 

 ammonium compounds. 



Attempts were made to prepare the corresponding nickel com- 

 pound, but they were unsuccessful. 



If instead of adding potassium bicarbonate and bromine to cobalt 

 carbonate, sodium acetate and bromine be added, a dark brown solution 

 is obtained. The same process for nickel gives a solution of the colour 

 of potassium bichromate solution ; but on boiling, a part of tlie nickel 

 salt comes down as a violet precipitate, whereas in the case of cobalt no 

 such precipitate comes down. These would seem to be lower oxidation 

 products than the one mentioned above ; for when to the brown cobalt 

 solution containing excess of bromine, potassium bicarbonate solution 

 is added, again the green solution referred to above is obtained. That 

 nickel should give only the lower oxidation product, and that, even this 

 should decompose on boiling is accounted for by the more basic nature 

 of nickel. 



