143 



face. There were no stalactites in this cavern, as there generally is 

 in those which contain no bones, and it was perfectly dry and free 

 from rubbish. 



From a note annexed to this letter by Sir Everard Home, the bones 

 alluded to appear to be the grinder of the upper jaw of the single- 

 horned rhinoceros. Two grinders, two tusks, and portions of two 

 tibiae of the brown or black bear ; and portions of bones of an ani- 

 mal of the deer kind. 



These specimens are deposited in the Museum of the College of 

 Surgeons. 



On the Aeriform Compounds of Charcoal and Hydrogen ; with an Ac- 

 count of some Additional Experiments on the Gases from Oil and 

 from Coal. By Willian Henry, M.D. F.R.S. %c. Read February 

 22, 1821. [Phil. Trans. 1821, p. 136.] 



In this paper, after adverting to the sources, properties, and com- 

 position of carburetted hydrogen obtained from stagnant water, and 

 of olefiant gas procured from the decomposition of alcohol ; and after 

 examining the agency of chlorine upon these compounds ; the author 

 proceeds to examine the gas procured by the decomposition of oil 

 and of coal at high temperatures. The former, or oil gas, is shown 

 to vary considerably in composition and properties, according to the 

 temperature at which it is procured; and though no temperature 

 short of ignition is sufficient for the decomposition of oil into per- 

 manent combustible gases, yet the lower the heat the more combus- 

 tible is the gas, and better suited to artificial illumination. 



In analysing these gases, Dr. Henry always found them mixtures 

 of olefiant, carburetted hydrogen, hydrogen, and carbonic oxide 

 gases. Dr. Henry separated the first by the action of chlorine, and 

 from the detonation of the residue with oxygen, as compared with 

 an artificial mixture of known composition, he ascertained the rela- 

 tive proportions of its components. 



It appears from the tables exhibiting these results, that in oil 

 gas the proportion of carbonic oxide is greater than in that from 

 coal, but that carburetted hydrogen is most abundant in the latter. 

 The proportion of hydrogen appears to increase in both as they are 

 formed at higher temperatures, and is always greatest in the latter 

 portions of coal gas ; but Dr. Henry never found that either oil or 

 coal gas, after the action of chlorine with the exclusion of light, pre- 

 sented a residue of pure hydrogen. 



In the concluding section of this paper, the author details some 

 experiments which led him to consider that portion of oil gas which 

 is condensible by chlorine, not as mere olefiant gas, but as a peculiar 

 compound, requiring nearly two volumes of oxygen more for its com- 

 bustion than an equal quantity of olefiant gas, and affording one 

 additional volume of carbonic acid ; he therefore thinks that it must 

 be considered either as containing a new compound of carbon and 



