On the Ammon'iure and Add of Cohalt. 231 



6. It is perfe£lly foluble in water. 



7. It decompofes all the alkaline fulphures from which it 

 precipitates the fulphur. 



8. It precipitates ammoniure of copper of a bright green, 

 and that of zinc of a pure white colour. 



9. It precipitates the fulphat of copper of the fame colour 

 as the ammoniure of that metal. 



10. It precipitates the nitrat of filver white; 



11. The nitro-muriat of tin the fame ; 



12. The nitrat of mercury of a clear ftraw colour ; 



13. The acetite of lead white. 



14. It does not make any fenfible change in folutions of 

 gold and platina. 



15. It precipitates lime-water in a white coagulum info- 

 hible in water, and fuper-faturated with acid. 



16. It precipitates the acetite and muriat of barytes. 



17. It is feparated from the water which holds it in folu- 

 tion by alcohol. 



18. Employed as a fympathetic ink, it is not coloured 

 green or blue like folutions of cobalt, but renders the paper 

 brown and then black when it has been expofed to a ftrong 

 heat, as is the cafe with other acids. 



19. With tinfture of gall-nuts newly made, it forms an 

 abundant yellowifli precipitate. 



ao. With a faturated folution of foda it gives an irregular 

 tranfparent fait foluble in water, but not deiiquefcent in the 

 air. 



21. With pot-afh it forms a fait cry ftalli fable in fquare 

 cryftals, tranfparent, and not deiiquefcent in the open air; 



22. With ammonia a fait foluble m its acid; 



23. With barytes an opake fait cryftallifable with diffi- 

 cultv. 



The prefcnce of an acid in zaffar made me fufpeft that 

 this acid might be of an arfenical nature ; but this doubt foon 

 vaniftied by comparing the charadlers of the two acids. 



ift, The arfcnic acid does not precipitate folutions of filver 



like the cobaltic acid. 2d, The arfeuic acid precipitates 



lime-water: this arfeniate is rcdilfolvcd by the acid as well 



js by a frefli quantity of lime-water. Tlie contrary is the 



7 cafe 



