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CONTKIBUTIONS TO THE KNOWLEDGE 



ties of carbon vapour, varying from 2*54 volumes to 4*36 

 volumes, from which it is evident that two gases undergoing 

 the same amount of condensation from the chlorine and sul- 

 phuric acid tests, might still differ in illuminating power to 

 the extent of more than 71 per cent. 



In his very carefully performed experiments upon Boghead 

 and Lesmahago cannels. Dr. Fyfe found that practically their 

 illuminating power was nearly equal, although the quantity 

 of hydrocarbons contained in the Boghead gas, as shewn by 

 the chlorine test, was 27 per cent., whilst the Lesmahago gas 

 contained only 17*6 per cent. ; and Dr. Fyfe suggested that 

 this equality of light might be owing to our not being yet 

 acquainted with the method of burning rich gases to ad- 

 vantage ; but on determining the quantity of carbon con- 

 tained in equal volumes of the Boghead and Lesmahago 

 hydrocarbons, I find that 17*6 volumes of the Lesmahago 

 hydrocarbon contain nearly as much carbon as 27 volumes of 

 the Boghead hydrocarbon, which satisfactorily demonstrates 

 this to be the cause of the equality in illuminating power. 



The following are the results of the experiments upon the 

 process applied to resin : — 



I— PRACTICAL RESULTS. 



Materials Comumed. 



Products Obtained. 



Average production of Gas per ton of Resin 32,080 cubic feet. 



Average production of Resin Oil per ton of Resin 70.3 gallons. 



Illuminating power of average Gas before purification, as ascertained by shadow 

 test, .75 cubic feet per hour = light of one short six candle. 



