HISTORY OP COBALT AND NICKEL. J51 



will be deposited on the sides of the retort, nitrous gas will 



be evolved, and the residuum obtained will be black oxide. 



The quantity will be iri the proportion of 1 25 or i 26 parts td 



100 of the metal in the solution. Hence we may infer, that the 



maximum of the oxidation of cobalt is between 25 or 26 of 



oxigen to a hundred parts of the metal. 



This oxide is not soluble either in the nitric or sulphuric Insoluble in 

 , . .. , . c . t • t .. acids without 



acid, without losing that portion of oxigen, which converts losing Bxigfe- 



it to the state of a maximum. 



With muriatic acid it gives Out oxigeri gas. 



It is insoluble both in ammonia and in potash. and in alkalies* 



The black oxide* heated for half an hour at the bottom of a Heat converts 

 retort, returns to the state of gray oxide by parting with Oxi- ,tto S ra y ox ' «*• 

 gen } and it is then capable of giving a blue tint to vitrifiable 

 substances. 



Messrs. Proust and Thalaker have met with the black Nativfc. 



oxide at Pavias, a day's journey from Valentia. It is found 



likewise in those ores of cobalt which are termed iitreats, or 



black ores. 



The corbonat and hidrat of cobalt are changed into black From carbe- 

 . , , ..,..,.,., , nat and hidrat, 



oxide by oxigenized muriatic acid. 



The nitrous and sulphurous acids dissolve the black oxide, Soluble iri ni- 

 forming with it nitrat and sulphat at a minimum p'uurob^aSds 



Muriat of Cob ah. 



The gray oxide disolves with heat in muriatic acid of 15 . Blue, oran- 

 The solution, whether hot or cold, is of a deep bllie : it cry- a ]idr*& * ' 

 stallizes easily, and the crystals are blue : this is the anhidrous 

 muriat. As soon as it has absorbed moisture, it becomes red. 



Muriatic acid of 15 yields much gas with the black oxide. 

 This solution is green as long as it retains any gas j but as 

 soon as it has lost it, it becomes blue. The blue traces of 

 muriat of cobalt dried on paper are anhidrous muriatic. When Green muriat 

 they are green, it is because the salt still contains muriat of ^S^ckd* 1 

 /riekel, which gives a yellow tinge, and thus forms green with 

 the blue. 



lis distillation. 

 Urged to redness in a luted retort, it is decomposed. diiiy in Heated, what 



E,a the 



touches the 

 glass is fcNteMP 



