200 Drs. Letts and Collie on the Salts of 



the gas were made without success ; thus proving that any 

 of the ethyl groups which are split off from the phosphorus 

 atom, if they do not form diethyl ketone, lose a hydrogen atom 

 and are evolved as ethylene gas. 



An interesting reaction was noticed between free sulphur 

 and the oxalate. The salt, when fused and heated gently to 

 about 160° C, gives, with free sulphur, a splendid deep indigo- 

 blue colour, which turns green and finally yellow on cooling. 

 The colour, however, reappears on heating ; but if too strongly 

 heated the sulphide of triethylphosphine is formed, and total 

 decomposition of the oxalate occurs. Many substances con- 

 taining sulphur, such as vulcanized indiarubber, gunpowder, 

 &c. give this blue colour when even the smallest particles 

 are heated with the oxalate on a porcelain crucible lid. Most 

 of the other salts of tetrethylphosphonium give this colour 

 with free sulphur when warmed, but none gave it in such a 

 marked manner as the oxalate. 



It is remarkable that the oxy-salts of tetrethylphosphonium 

 should so easily give sulphide of triethylphosphine when fused 

 with sulphur, while the oxide of triethylphosphine itself is 

 totally unacted upon by sulphur under similar conditions. 



Action of Heat on the Cyanide of Tetrethylphosphonium. 



As all the preceding experiments were performed with 

 salts of the phosphonium derived from oxy-acids, and as in 

 each case part of the oxygen was eliminated in the form of 

 oxide of the tertiary phosphine, we considered that it would 

 be of interest to study the action of heat on some of the salts 

 of the phosphonium which contained no oxygen, and which 

 therefore could not yield that body. 



We fixed upon the cyanide to commence with as being 

 likely to decompose at a lower temperature than any other 

 haloid compound. 



The cyanide of tetrethylphosphonium was obtained in solu- 

 tion by double decomposition between the iodide and cyanide 

 of silver. It was found that when this solution \v r as concen- 

 trated on a water-bath partial decomposition occurred, and 

 hydrocyanic acid was evolved together with an inflammable 

 gaseous hydrocarbon. This decomposition being no doubt 

 due to the action of the water on the cyanide, probably in the 

 following manner : — 



(C 2 H 5 ) 3 P<^ 5 + H 2 = (C 2 H 5 ) 3 PO + HON + C 2 H 6 . 



The solution was transferred to a distilling flask and heated, 

 when hydrocyanic acid, cyanogen gas, a little free triethyl- 



