iSoMl Eni^titution of ffiteat ISrifaiiu 



WEEKLY EVENING MEETING, 



Friday, January 16, 1880. 



George Busk, Esq. F.R.S. Treasurer and Vice-President, 

 in the Chair. 



Professor James Dewar, M.A. F.R.S. 



FDLLERIAN PROFESSOR OF CHEMISTRY R.I. 



(Abstract.) 



Investigations at High Temj^eii-atures, 



I INTEND to discuss on the present occasion the results of a preliminary 

 study of the chemical interactions taking place at the temperature of 

 the electric arc, and the inferences which can be deduced from a series 

 of radiation experiments as to the probable temperature of this source 

 of heat. 



On the Formation of Hydrocyanic Acid in the Electric Arc. 



The conclusion that the so-called carbon spectrum is invariably 

 associated with the formation of acetylene,* induced me to try and 

 ascertain whether this substance can be extracted from the electric 

 arc, which invariably shows this peculiar spectrum at the positive 

 pole, when it is powerful and occasionally intermittent. For this 

 purpose the carbons were used in the form of tubes, as shown in the 

 following figure, so that a current of air could be drawn by means of 

 an aspirator through either pole, and the products thus extracted 

 from the arc, collected in water, alkalies, and other absorbents. Gases 

 may be led through one of the poles, and suction induced through the 

 other, in order to examine their effect on the arc and the products 

 obtained from it. 



The following results were obtained by means of the Siemens and 

 De Meritens magneto-machines, recently presented to the Royal Insti- 

 tution through the munificence of the Duke of Northumberland and 

 Mr. Siemens : — 



Air drawn by an aspirator from the arc through a drilled negative 

 carbon, and the gases passed through potash, iodide of potassium, and 



o 



* As suggested by Pliickor, Angstruiu, and Thale'n, 

 Vol. IX. (No. 72.) t 



