874 SALICYL. 



immediately assumes an emerald green colour, and soon deposits 

 very brilliant plates of the same colour while at the same time 

 the liquid becomes colourless. When this salt is heated with 

 concentrated acids, it gives a salt of copper and an ammoniacal 

 salt, while the hydrated salicylous acid is set at liberty. Potash 

 ley does not decompose this salt except imperfectly ; sulphu- 

 retted hydrogen not more completely, even after one or two 

 hours' action. If, however, it has first been made to boil with 

 an acid, the decomposition by sulphuretted hydrogen is in- 

 stantaneous. 



Salhydramidide of 'iron , 3 (H,C 14 H 5 NO) + Fe 2 O 3 . This com- 

 pound, which Dr. Ettling succeeded in forming, is analogous 

 in composition to the copper compound. It precipitates in red 

 flocks, which gradually acquire some lustre, becoming granular. 

 Hydrochloric acid does not alter it in the cold, but when the 

 acid is pretty concentrated and assisted with heat the compound 

 is dissolved and salicylous acid separated. 



Salhydramidide of lead. There appear to be two compounds 

 of salhydramide with oxide of lead, but they have not been 

 obtained in a state of purity. 



Melanic acid (anhydrous), C 10 H 4 O 5 . Salicylite of potash 

 exposed in a humid state to air absorbs oxygen and undergoes 

 decomposition, becoming first green and then black. The only 

 products are acetate of potash and an insoluble black powder 

 resembling lampblack, which Piria terms melanic acid. This 

 acid contains no water of combination ; it is soluble in alcohol 

 and ether, and very soluble in alkalies. 



Salicylic acid, HO-f C 14 H 5 O 5 =HO,SaO. This acid is pro- 

 duced by heating salicylous acid with an excess of dry hydrate 

 of potash, till the brown mass becomes white, which is attended 

 with the escape of hydrogen gas. The salicylic acid is liberated 

 by adding an excess of hydrochloric acid, and is purified by 

 repeated crystallizations. This acid crystallizes both from solu- 

 tion and sublimation very much like benzoic acid. It may be 

 volatilised without decomposition. It is sparingly soluble in 

 cold water, very soluble in hot water and in alcohol. It reddens 

 vegetable colours and decomposes the alkaline carbonates. 

 Salicylate of silver is an insoluble white precipitate, anhydrous. 

 (Piria). 



Chlorosalicylic acid, chloride of salicyl, chloride of spiro'ile ; 



