PRODUCTS FROM COAL. 



45 



short sixes ; the second portion required nearly seven cubic feet to produce 

 the same effect. 



The analysis of 100 cubic inches of the first portion was as follows : 



Olefiant gas 

 Carburetted hydrogen 

 Carbonic oxide and hydrogen 

 Carbonic acid 

 Sulphuretted hydrogen 



8 



72 



13 



4 



3 



100 



The second portion was not analysed. 



In Mr. Nicholson's Philosophical Journal for June 1805, and in the Trans- 

 actions of the Royal Society for 1808, will be found a communication from 

 Dr. Henry, on the illuminating power of combustible gases obtained from coal 

 admitting of more exact appreciation than the optical method by the compari- 

 son of shadows. The method to which he gave the preference was the deter- 

 mination of the quantities of oxygen gas consumed, and of carbonic acid 

 formed by the combustion of equal measures of the different inflammable 

 gases, that gas having the greatest illuminating power which in a given 

 volume condensed the largest quantity of oxygen gas. He found that 100 

 measures of pure hydrogen required only 50 of oxygen for its saturation, 

 whereas 100 measures of olefiant gas required 284 of oxygen for its complete 

 combustion : the former produced no carbonic acid, the latter produced 179 

 measures. The following Tables will show the results he obtained. 



It appears from these experiments that gas from cannel-coal has, with 



* The inferior illuminating power of this gas is owing to the presence of so large a portion of 

 nitrogen. It certainly is a more than average proportion for any gas. 



