OF THE MANUFACTURE OF OAS. 



118 



temperature of the gas does not become reduced to 32° unless 

 the tube be inconveniently long and the stream very slow; 

 and if any hydrocarbons are condensed, they have not time 

 entirely to deposit, but a portion is carried forward in the 

 vesicular condition, until on emerging from the refrigerator 

 it is again gasified by the increasing temperature. To avoid 

 these errors an apparatus* was employed in the following 

 experiments, by means of which the volume of the gas satu- 

 rated with watery vapour, and at the temperature of about 

 60°F., could be accurately ascertained, and the gas then trans- 

 ferred without loss into the refrigerator, where it was exposed 

 to 32'^ for not less than one hour; it was then transferred 

 into the measuring portion of the apparatus, the pressure 

 upon the gas being constantly preserved equal to that of the 

 external atmosphere; when the gas had again become perfectly 

 saturated with watery vapour, its volume at 60°F. was again 

 ascertained ; the difference gave the loss of hydrocarbons in 

 the refrigerator. I have not submitted all the gases to this 

 test ; but it has been applied to a sufficient number to show 

 that those made by the new process, so far from losing more 

 illuminating materials by exposure to cold, lose in all cases 

 less than the corresponding gas made by the usual process 

 from coal alone. 



The following are the results of these experiments : — 



NAME OF GAS. 



Cubic feet of hydrocarbons 

 condensed from 100 cubic 

 feet of gas on exposure to 

 a cold of 32" p. 



Boghead 



" with water-gas 

 Methyl 



" with water-gas 

 Ince Hall 



4.42 cubic feet, 

 .24 " 

 .33 « 

 .07 " 

 .37 " 



* This apparatus will be fiilly described along with the one used for the 

 analysis of the gases. 



Q 



