Mons. R. Piriaow the Combinations. ofSalicijle. 217 



is a yellow crystalline body, soluble in alcohol and tether, 

 nearly insoluble in water ; the addition of weak alkalies causes 

 the disengagement of ammonia ; by heating it in an acid fluid 

 it is decomposed, a salt of ammonia being formed, and chlo- 

 ride of salicyle being set free. Chlorosamide consists of 

 Atoms. 



Carbon . . . 



14 = 



= 84 



56-52 



Hydrogen . 



5 



5 



3-30 



Oxygen . . . 



2 



16 • 



10-57 



Nitrogen . . 



4 

 5" 



18-4. 



6-23 



Chlorine . . 



1 



36 



23-38 



Atomic weight. . . 159"4< 100 



When gaseous ammonia is made to act on bromide of ben- 

 zoyl, a compound called h-omosamide results ; its composition 

 is identical with chlorosamide, with the substitution of the 

 chlorine by its equivalent of bromine. 



Action of the air on Salicide of Potassium. 



When salicide of potassium in a perfectly dry state is ex- 

 posed to the air, or to an atmosphere of oxygen gas, it under- 

 goes, as has been already observed, no obvious change; but 

 if this salt be previously moistened, it, by a similar exposure, 

 alters in colour, its surface becomes covered with green 

 specks, and it darkens in hue until the whole mass becomes 

 completely black. If the moist salicide of potassium be placed 

 in a receiver of oxygen gas inverted over mercury, the latter 

 will be observed to rise rapidly in the glass, from the absorp- 

 tion of its gaseous contents. When the black, changed, salt 

 is digested in water, a certain portion dissolves, and a soot- 

 like powder is left ; this should be collected, washed, and 

 dried. This black compound dissolves readily in alcohol and 

 aether, but is insoluble in water; it dissolves in alkaline solu- 

 tions, forming saline compounds, from which the black pow- 

 der is thrown down unchanged by acids. This substance 

 appears to possess properties of a decidedly electro-negative 

 character, and from this circumstance, as well as from its co- 

 lour, it has been termed melanic acid, a name unhappily chosen, 

 as it has already been applied to an ingredient in certain mor- 

 bid animal secretions. 



Melanic acid decomposes alkaline carbonates, forming saline 

 combinations, attended with the evolution of carbonic acid 

 gas. When heated this acid burns slowly, but without flame, 

 and leaves no fixed residue. 



Melanate of silver was prepared by precipitating a solution 

 of melanate of ammonia by nitrate of silver j the precipitate 



