1819.] Dr. Henry's Experiments on the Gas from Coal. 337 



Product. 

 oz. dr. oz. dr. 



A cubic foot weighs ... 1 : 03 

 Consumes half a cubic. 



foot of oxygen 0:11 



1 : 14 Carbonic acid 1 : 14 



4. Olejiant Gas, or Bicarburctted Hydrogen. — This has been 

 demonstrated to be a compound of nearly 85 by weight char- 

 coal, and 15 hydrogen, without any oxygen. It is a little 

 lighter than common air, viz. in the proportion of about 974 to 

 1000. It surpasses all other gases in the brightness and density 

 of its flame. Its name was originally derived from the property,, 

 which it possesses, of being speedily and entirely condensed, by 

 rather more than an equal volume of chlorine gas, into a liquid 

 resembling oil in appearance, but since shown to approach more 

 nearly to the nature of ether. 



Products, 

 oz. dr. oz. dr. 



A cubic foot weighs. ..1:3 2 cubic feet carb. acid. . 3 : 10 

 Consumes 3 cub. feet of 



oxygen 4:0 Water 1 : 09 



5:3 5 : 03 



Olefiant gas I found to be one of the products of the distilla- 

 tion of oil and of bees' wax, and was led, therefore, to suggest, 

 that the wick of a lamp or candle, surrounded by fiame, is to be 

 -considered as a bundle of ignited capillary tubes, into which the 

 melted inflammable matter is drawn, and there resolved, not 

 into a condensible vapour, but into olefiant and carburetted 

 hydrogen gases. In the gas from coal, also, I detected the 

 presence of olefiant gas, by the test of the action of chlorine. 



In the second series of experiments,* I submitted to distilla- 

 tion, on a small scale, various kinds of coal, from different parts 

 of the kingdom. The aeriform products, at. different stages of 

 the process, were kept apart, and were separately analyzed. 

 From coal distilled in small iron tubes or retorts, which, when 

 filled, were placed at once in a low red heat, small quantities of 

 sulphuretted hydrogen and carbonic acid gases came over at first, 

 in mixture with the other gases, but in a gradually diminishing 

 •proportion, till at length, in the last products, they were not. 

 discoverable at all. The production of olefiant gas observed the 

 s;une order, and a gradual diminution took place, as the process- 

 advanced, in the combustibility of the gas, as determir.ed by its. 

 requiring less and less oxygen for saturation. A grjat variety 

 was ascertained to exist in the quality of the gas from different" 



* Phil. Trans. 1803, p. £3.\ 



Vol. XIV. N° V. Y 



