^yn: lr:>^ ux....>i^..~.- .. Add of CohaJt. 220 



9. This folution is precipitated by the pruffiat of pot-afh 

 of a blueifli-green colour, which does not change. Tt is not 

 precipitated by the -gallic acid, but the mixture acquires a 

 darker colour. In other refpefts this iolution exhibits all the 

 phenomena of a common folution of cobalt in the fame acid. 



10. The muriatic acid diffolves exceedingly well the yellow 

 oxyd, and affumes a beautiful highly-charged green colour. 

 This colour immediately difappears with the nitric acid as 

 well as with a little water, but it reappears by the addition 

 of a little of the muriatic acid well concentrated. 



Of the pure Ammoniure of Cohalt. 



11. The yellow oxyd diffolves entirely in ammonia, and 

 forms pure ammoniure of cobalt. This ammoniure has a 

 yellow, and fometimes a rofe, colour. It is not decompofed 

 by acids. It is deprived of its colour by the muriatic acid. 

 The pruffiat of pot-aHi changes it to grey, and occafions after- 

 wards a depofit of the fame colour. The fulphure of pot-afli 

 makes it aflhme a dark colour inclining to black, and preci- 

 pitates from it fulphure of cobalt *. The borat (alkaline) of 

 foda is decompofed by it, and precipitated into borat of cobalt 

 of a very white colour. 



On the Acid drawn from the Ammoniure of Cohalt, and 

 its Properties, 



12.- The red fubftance of the preceding experiments was 

 feparated from the yellow oxyd. For this purpofe I evapo- 

 rated in the fun liquid ammoniure ; and when it was reduced 

 to about the fourth of its volume, and no longer precipitated 

 in a fenfiblc manner yellow oxyd, I filtered it through paper. 

 What pafTed had a dark red colour, like decoftion of cochi- 

 neal. This liquor emitted no odour, but had a very pun- 

 gent tafte : it was again expofed to the fun till it was per- 

 fcftly deficcated. 



13. The remaining mafs was diffolved in diftilled water, 



• The fulphureof cobalt dried in the air appronches in colour to zafFar. 

 When rubbed on paper it affumes a metallic fpkndour like the greater 

 part of the other metallic fulphures : when heated it emits a fulphiireous 

 odoai, and influmes when thrown on burning coals, 



which 



