202 Dr. Hofmann on Chloranil. 



to volatilize at 302° F., and between 410-428° F. the subli- 

 mation is rapid ; it'it be heated above this temperature it melts, 

 and is finally carbonized. The sublimate has the appearance 

 of an extremely soft, light, iridescer.t powder, which remains 

 intact with acids, but when treated with alkalies is changed 

 with the greatest facility. When the crystals are drenched 

 with a dilute potash-ley, they acquire immediately a dark co- 

 lour with a shade of green, but on the application of heat dis- 

 solve to a blood-red fluid, from which purple needles of an 

 organic salt are deposited upon cooling. These needles, when 

 immersed in dilute hydrochloric acid, assume, without altering 

 their form, a bright red colour. They are quite insoluble in 

 very dilute acids, but dissolve in pure water with a beautiful 

 violet hue. By the addition of hydrochloric acid the liquid 

 is discoloured immediately, and after some time the red crystals 

 again deposit. 



There can be no doubt from the foregoing that the sub- 

 stance obtained from the hydrate of phenyle and Erdmann's 

 chloranil are identical. 1 have notwithstanding made some 

 combustions of this compound. The analyses were however 

 made with a product which was only recrystallized from al- 

 cohol, and not sublimed ; the substance was therefore not 

 quite pure, a circumstance which Erdmann had found pre- 

 viously. In five analyses this chemist always obtained a con- 

 stant excess of carbon : my analyses were also encumbered 

 with the same fault, owing to which there is a discrepancy be- 

 tween the chlorine found and that of theory. 



I. 0'5845 grm. of substance ignited with chromate of lead, 

 gave 0*6474 grm. of carbonic acid and 0'02]2 grm. water. 



II. 0*461 5 grm. of substance ignited with chromate of lead, 

 gave 05090 grm. of carbonic acid and 0*0120 grm. water. 



III. 0*2555 grm. "of substance ignited with lime and dis- 

 solved in nitric acid, gave 0*5820 grm. of chloride of silver. 



These numbers, represented in the 100 parts, give, — 

 I. II. III. 



Carbon . 30*20 30*07 



Hydrogen 0*40 0*28 



Chlorine 56*20 



Erdmann found as a mean of five combustions of the chloranil 

 crystallized from alcohol, 30*20 per cent, carbon *. The fol- 

 lowing is the theoretical composition of the chloranil : — 

 12 equivs. Carbon . . 900*00 29*33 



4 equivs. Chlorine . . 1770*60 57*66 



4 equivs. Oxygen . . 400*00 13*01 



3070-60 100*00 



* Carbon taken at 75. 



