258 



Professor Deioar 



[Jan. 16, 



atarch paste, gave no reaction for the presence of nitrites. The potash 

 contained sulphides. 



Hydrogen led in through the positive pole, and the gases extracted 

 as above gave the well-known acetylene compound with ammoniacal 

 sub-chloride of copper ; while, at the same time, a wash-bottle con- 

 taining water gave distinct evidence of the presence of hydrocyanic 



acid. 



Fig. 1. 



A hydrogen flame burning between the carbon poles gave no sul- 

 phides or hydrocyanic acid, when treated in the above manner. The 

 condensed water from the combustion gave the reaction for nitrites. 



Air drawn through the negative carbon gave considerable quanti- 

 ties of hydrocyanic acid, which was greatly increased by extracting 

 the gases through the positive carbon. Air was aspirated at the rate 

 of about one litre per minute. 



The same carbons used with the long arc of the De Meritens 

 magneto-machine gave no hydrocyanic acid. 



Carbons purified in chlorine and hydrogen gave with De Meritens' 

 arc nothing ; with Siemens' and a draught of air through the negative 

 pole, a small quantity of hydrocyanic acid, but a larger yield when 

 the positive pole was used. The gases extracted from the arc after 

 the absorption of the hydrocyanic acid contained acetylene. If the 

 carbons are not purified, sulphuretted hydrogen is always found along 

 with the other gases. 



The inference drawn from the above experiments is that the high 

 temperature of the positive pole is required to produce the reaction, 

 which is in all probability the result of acetylene reacting with free 



