SUPPOSED COBALTIC ACID, 



307 



hot. The filtered fluid had a light colour, and perceptible boiled in water 



tafte. I evaporated it in a capfule of porcelain, and towards 



the end of the evaporation it became turbid. I continued to 



evaporate until the fluid was f educed to about one hectogram 



by cooling, and obtained needle formed cryftals. The mixture Cryftals obtain- 



was filtered with agitation ; the cryftals remained upon the ^ ^y evapora- 



filter, and the fluid palled very tranfparent of a bright yellow 



colour. Citizen Brugnatelli in making this experiment has 



Hot remarked the cryftallization ; he has only obferved a 



white matter which was converted to a rofe colour by the 



contact of the air, and fuppofed by him to be the oxide of 



cobalt. The needle formed cryftallization which I obtained It gave out 



afforded a confiderable difengagement of arfenic as foon as it ar emc y ea ' 



was heated. When carefully examined it was proved to be the and was arfeni. 



arfeniate of cobalt, and not the oxide as had been announced, ate of cobalt. 



This fa<5t is no doubt of little confequence to the difcoveries 



of Citizen Brugnatelli ; but neverthelefs it might ferve to fup- 



port my opinion, if the refults of my experiments were not 



more than fufficient to prove that the cobaltic acid has no ex- 



iftence. 



The liquids of the 1 ft, 2d, and 3d experiments, which Examination of 

 proved to be acid, and of the fame nature, were fubje&ed to the acidli< l uors ' 

 the following trials, and comparatively with the arfenic acid. 



Firft trial. This acid liquor is precipitated by fulphurated Sulphurated hi- 

 hidrogen, and by the alkaline hidro-fulphurets of a yellow dSubhTet 

 colour fimilar to opiment, or the fulphuret of arfenic. This of arfenic. 

 precipitate is in fact fulphuret of arfenic, and not fulphur pre- 

 cipitated, as Citizen Brugnatelli has fuppofed. 



Second trial. It precipitates the ammoniuret of copper Xt forms arfeni.- 



of a blueifh green colour. This property belongs to the arfe- w j t j, t h e ammo . 



nic acid. The combination is known by the name of arfeniate niuret of that 



c metal. 



of copper. 



3. Sulphate of copper mixed with this fluid affords a pre-£* Jifte^fc 

 cipitate of the fame colour as the ammoniuret of this metal, p^r is the fame 

 The arfenous acid alfo poffefTes this property not fo eminently as that of ' he 



. . , . . . ... - ■ .. . . arfeniate of co- 



as the pretended cobaltic acid, but a fimilar precipitate may bait. 

 be obtained by ufing the arfeniate of cobalt formed artificially. 

 In th* cafe the refults are the fame, and no difference can be 

 perceived. 



4. It precipitates the nitrate of filver of a white col6ur. K alfo acls hke 

 tm r • • i in • i- arfeniate of co- 



1 he arlenic acid alio enjoys this property. bait on nitrate 



X2 5. The officer j 



