1870.] Contributions towards the History of Thiobenzamide. 400 



The analysis of these crystals leads to the formula 



C 7 H. N O. 



But from their formation as well as their general properties we are con- 

 vinced that they are the trimolecular combination, the phenylic cvanurate, 



1C.H.0 



G„ H 13 N3 0 3 =C 3 N 3 lc s H s O 

 J C 0 II 5 O 



which corresponds to the methyl compound described in the beginning of 

 this note. 



The melting-point of the crystals was found to be 224°, somewhat lower 

 than that of the isomeric compound (264°) which one of us* has lately 

 examined. 



The latter, which must now be regarded as the phenylic isocyanurate, 

 is easily distinguished from the new cvanurate, both by its crystalline 

 form and behaviour with solvents. It has yet to be determined whether 

 the phenyl compound, like the methyl one, is changed under the influence 

 of heat into the cvanurate already known. 



We cannot close this communication without thanking Messrs. R. 

 Bensemann and K. Sarnow for the assistance they have rendered us in 

 carrying out these experiments. 



II. " Contributions towards the History of Thiobenzamide." 

 By A. W. Hofmann, LL.D., F.tt.S. Received May 27, 1870. 



When a stream of sulphuretted hydrogen is passed through a solution 

 of benzonitrile in alcoholic ammonia, the liquid, after the lapse of a few 

 hours, deposits fine yellow needles, which are the thiobenzamide, 



C 7 H-,S] 

 C. II. NS= II \ X, 

 H J 



discovered by M. Cahours. It can be obtained in a pure state by recrys- 

 tallization from boiling water. 



When a cold saturated alcoholic solution of this body is mixed with 

 an alcoholic solution of iodine, the latter is immediately decolorized with 

 separation of sulphur. If the addition of iodine solution be continued 

 until even after a short boiling free iodine remains, which can readily be 

 detected by starch-paste, the solution filtered from the sulphur, and poured 

 into water, solidifies to a mass of white interlaced needles, which can rea- 

 dily be freed from adhering hydriodic acid by washing with cold water. 



This substance can be obtained pure by repeated crystallization from 

 boiling alcohol. In this state it forms long shining snow-white needles, 

 which melt at 90°, and distil without decomposition at a very high tempera- 

 ture. The compound also dissolves in ether, chloroform, and benzol. At 

 first I believed it to be free from sulphur. Its alcoholic solution can be 



* ITnfmnmi. IVridito der Chem. Gesellsdbu z. Berlin, ITT. 268. 



