M. Hlasiwetz on Isopurpuric Acid. 131 



syi'upy consistence, is inodorous, and colours the skin yellow. It 

 appears to combine with ammonia and potash. 



Dinitrocresylic Acid, C'* H« (NO*)^ 0^ is best obtained by 

 warming au aqueous solution of sulphocresylic acid with a little 

 nitric acid and then allowing the mixture to cool. A resinous 

 body separates, which is filtered off, and the filtrate then heated 

 to boiling, and dilute nitric acid added. An oil separates which 

 has the above composition, and in its properties resembles the 

 mononitrated compound. 



Trinitrocresylic Acid, C^^ H* (NO^)^ 0^— This is obtained by 

 heating a solution of sulphocresylic acid with nitric acid. The 

 resinous body which at first separates is filtered off, and the 

 filtrate evaporated with excess of nitric acid to dryness : the 

 biuitro-compound at first formed is changed into trinitrocresylic 

 acid, which along with oxalic acid is contained in the residual 

 mass. 



Trinitrocresylic acid crystallizes from alcohol in fine orange- 

 yellow needles. It dissolves in 450 parts of water at 20° : picric 

 acid dissolves in 80 parts at the same temperature. Heated to 

 above 100° it melts to an oil, which solidifies, on cooling, to a 

 crystalline mass. Treated with hypochlorite of lime, the odour 

 of chloropicrine is obtained. Trinitrocresylate of potash consists 

 of fine yellow needles, very soluble in watei", and which detonate 

 strongly when heated. 



The study of the reduction of organic nitro-compounds has 

 hitherto been limited to that of the action of sulphide of 

 ammonium, of sulphite of ammonia, of acetate of iron, and of 

 nascent hydi'Ogen. Hlasiwetz * has examined the reducing action 

 of cyanogen on picrate of potash ; and the curious results he has 

 obtained promise for this agent a more extended use. 



When hot concentrated solutions of cyanide of potassium and 

 of picric acid are mixed, the solution immediately assumes a 

 blood-red colour, becomes filled with fine dark crystals, and, on 

 cooling, solidifies to a mass of crystals. The mass smells strongly 

 of ammonia and of hydrocyanic acid : it is expressed between 

 bibulous paper, subsequently washed with a small quantity 

 of cold water, again pressed, and then dissolved in hot water 

 and filtered. The purple-coloured filtrate soon deposits brownish- 

 red laminar crystals with a green lustre. These form the jiotash 

 salt of a new acid, which the author names isopurpuric acid. The 

 potash salt is but little soluble in cold, but readily so in hot 

 water. The solution has a most intense purple colour. Heated 

 ou platinum, the salt detonates. Its solution precipitates the 



* Liebig's Annalen, June 1859. 

 K2 



