Dr. Hofmann on Chloranil. 201 



united influence of oxygen and chlorine. I commenced my 

 investigation with the hydrate of phenyle, and selected as a 

 means of oxidation a mixture of hydrochloric acid and chlo- 

 rate of potash, in which oxygen and chlorine are disposable. 

 When hydrate of phenyle in a porcelain basin is treated with 

 strong hydrochloric acid, and there is added at intervals small 

 crystals of chlorate of potash, a violent reaction ensues, and 

 the colourless oil acquires a reddish-brown colour and inspis- 

 sates. If the action has lasted sufficiently long, the whole 

 mass changes to a light yellow crystalline matter, which is 

 no other than chloranil. As it takes a long time to ensure 

 perfect decomposition, it is advisable towards the end ol the 

 process to apply heat, in order to promote the action. I 

 have endeavoured to shorten the time by employing an alco- 

 holic solution of hydrate of phenyle; the decomposition then 

 takes place indeed quicker, but a great quantity of chlorate 

 of potash is wasted by the conversion of the alcohol into 

 acetic aether. When alcohol is used, the addition of strong 

 hydrochloric acid, or too quick an introduction of large quan- 

 tities of chlorate of potash must be avoided, as the mass in- 

 flames readily with explosion. These explosions even some- 

 times lake place when no alcohol has been added ; it is there- 

 fore always advantageous to conduct the operation in basins. 



If a boiling saturated aqueous solution of hydrate of phe- 

 nyle is employed it saves time, and also chlorate of potash ; or 

 a watery extract of coal-gas naphtha may beat once taken, as 

 it contains aniline and hydrate of phenyle, both being con- 

 vertible into chloranil. The produce is in this way, however, 

 very limited, owing to the slight solubility of these two com- 

 pounds in water*. 



To purify the chloranil it is only necessary to affuse with 

 water, which dissolves any adhering chloride of potassium, 

 and to crystallize from alcohol. This menstruum dissolves the 

 chloranil with difficulty in the heat; and on cooling the whole 

 deposits. 



I have compared minutely the properties of the substance 

 obtained in this way with those given by Erdmann in his 

 treatise on chloranil, and find that they agree perfectly. The 

 body I procured from hydrate of phenyle, as was before re- 

 marked, is insoluble in water, dissolved with difficulty by alco- 

 hol, but more easily by aether, and crystallizes from the two 

 latter solvents in shining golden-yellow plates ; the mother- 

 liquor assumes a violet tint when exposed to the air. It begins 



* In an experiment where I treated the coal-gas naphtha with the oxi- 

 dizing mixture there was no chloranil found, apparently owing to its quan. 

 tlty being so minute when compared with that of the other products. 

 Phil Mag. S. 3. Vol. 26. No. 172. March 1845. P 



