136 PROCEEDINGS OP THE AMERICAN ACADEMY 



different properties, without correcting his previous statements or 

 drawing attention to the difference. The results obtained in that 

 paper agree entirely with Gal's previous statements. 



I have, therefore, also made this salt in large amounts from pure 

 prussic acid (bpt. 26°. 2) and hydriodic acid, dried by means of 

 phosphorus pentoxide, and can confirm Gautier's detailed state- 

 ments in Annales de Chimie et de Physique, [4.], XVII. 143, in 

 every respect. The substance is extremely unstable, and can only 

 be dried about a minute over sulphuric acid in vacuum; in ten 

 minutes such marked decomposition takes place that no analysis 

 of it can be carried out. 



From the results obtained above in the case of the isonitriles, 

 and from the experiments of Claisen and Matthews, it becomes 

 very probable that all the salt-like products obtained from prussic 

 acid and the halogen hydrides are constituted according to the gen- 

 eral formula, 2 HNC, 3 HX. These compounds are, as Claisen 

 and Matthews * already regard as probable, salts of imidoformyl 

 haloids, 



2 HN=C*Jj , HC1 ; 2 HX=C^ r , HBr ; 2 HN=C ' , HI. 



Gautier has already shown in his last paper f that hydrobromic 

 acid forms with prussic acid a salt of the formula 2 HXC, 3 HBr. 

 He thereby corrects his previous statements, as well as those of 

 Gal. It is, therefore, highly probable that the salts HNC,HC1, 

 and HNC, HI, analyzed formerly, may have contained mechani- 

 cally enclosed prussic acid, since the substances were only dried 

 a few seconds over sulphuric acid in a vacuum. 



Furthermore, some new observations have been made which 

 make it improbable that imidoformylchloride, 



HN=C^, 



and phenylimidoformylchloride, 



C 6 H 5 N=Cq2 , 



are capable of existence. It is to be expected that these substances 

 should be volatile liquids. On treating potassic formiate with 

 2 molecules of phosphorus oxychloride, or with 3 molecules of phos- 

 phorus trichloride, a violent reaction sets in at 0°, and a mixture 



* Ber. d. chera. Ges., XVI. 311. t Loc cit., XVII. 141. 



