422 MESSRS. R. S. HUTTON AND J. E. PETAVEL ON ELECTRIC 



occurring in quite ordinary cases, is far from exhausted, and practically nothing is 

 known of the modifications introduced by abnormal conditions, such for instance as 

 the combination of high pressure and high temperature. 



The present research has been undertaken with a view to determine the correlation 

 between the physical conditions and the chemical effects in the electric furnace, and 

 more especially to ascertain the direct results produced by high gaseous pressures. 

 In such work, if it is to be of real value, it is necessary to carry out the experiments 

 on as large a scale as the limitations of cost and labour will permit ; it is also 

 particularly desirable to provide means for the modification of the various factors 

 within the widest possible range. The chief factors being power, current, electro- 

 motive force, and above all, pressure. 



In work carried out during preceding years under atmospheric pressure the 

 necessity for employing now one type, now another of electric furnace determined us 

 to select an apparatus suitable for both open and smothered arc, as also for resistance 

 heating.* 



The above considerations accentuated the already somewhat difficult task of 

 designing a furnace suitable for high gaseous pressures. For, as already suggested, 

 it would have been of little use to provide for a slight increase of pressure over that 

 of the atmosphere. 



The apparatus constructed is capable of employment for electric heating according 

 to the most varied type of furnace, and has frequently been used for pressures as high 

 as 200 atmospheres. We were thus in a position to extend our direct experimental 

 study up to the limits which engineering difficulties set to practical application. 



With regard to the experimental work, the first step was to investigate the 

 additional effect of high pressure upon the more characteristic electric furnace reactions, 

 it being obviously advisable to start by repeating the better known preparations, 

 retaining as far as possible all other conditions similar to those at present in use. 



It is with a general investigation of this character that our communication has 

 to deal. 



To avoid burdening the description of the work with the many numerical results, 

 we have collected these in tables in an appendix to the paper. 



DESCRIPTION OF APPARATUS. 

 Large High-Pressure Furnace. 



From what has been said above it will be clear that an apparatus was necessary 

 capable of being adapted to very varied requirements. 



This end was met by designing a large steel enclosure of about 20 litres capacity, 



* We have frequently had occasion to divide the enclosure into a number of separate chambers, e.g., for 

 absorbing gaseous products inside the furnace, as also for a condensing chamber in volatilisations ;ind 

 distillations. 



