230 On the Ammonlure and Acid of Cobalt. 



which was tinged of a beautiful ruby colour. This folution 

 manifefted an unequivocal chara<9:er of acidity. On cooling, 

 it depofited fome fmall brilliant cryftals, which I found to be 

 a combination of the acid with ammonia. As this acid 

 feemed to be diftinft from all the other acids, I have given 

 it the peculiar name of the cobalttc acid. 



14. To afcertain whether the cobaltic acid could be fepa- 

 rated from the ammoniure of cobalt by means of heat, I fub- 

 jeAed a pound of it to didillation in a retort. After three- 

 fourths of the liquid had pafled into the receiver I flopped 

 the diftillation, and found that the retort contained a liquid 

 rendered turbid by the yellow oxyd precipitated. I decanted 

 the liquid after the precipitate had depofited itfelf, and eva- 

 porated it to drynefs. The refiduum was yellowifh, and 

 partly foluble in water, to which it comiiiunicatcd a yellow 

 tint. This folution pofleffed all the acid charafters of the 

 red liquid of No. 15. 



15. In another experiment I put a pound of the ammo- 

 niure of cobalt into a retort, and carried the dillillation to 

 drynefs. The cooled matter which remained at the bottom 

 of the retort was blue ; but it had this colour only at its 

 furface, being internally yellow. After fome hours this blue 

 colour difappeared, and the niafs aflumed a red colour. 



16. A remarkable difference between the refiduum of the 

 evaporation in the fun and that by fire is, that the latter gave 

 up to the water the cobaltic acid alnioft colonrlefs, fo that 

 the folution, filtered cold, was almoft as limpid as water. I 

 remarked befides, that by the latter procefs the acid does not 

 contain any, or contains very little, of cobalt of anunonia 

 [cobalt d' ammoniaque) . 



I {hall now enumerate the principal charaAers by which 

 the new acid is diftinguifhed, 



1. It prefents itfelf under a concrete form, and is not vo- 

 latilifed by fire. 



2. It is fometiraes of a red colour, fometimes pale yellow, 

 and at other times entirely colourlefs. 



3. It has no fmell. 



4. It has an acid, pungent, but not difagreeable tafte. 



5. It gives a tinge of bright red to an infufion of turnfol. 



6. It 



