1821.]'] . Rot/al Society. '■ 229 



at length 1ft the paper. The chief of these is the complete exclu- 

 sion of light, for in that case olehant gas alone is condensed, but 

 even the faint light of a cloudy day was found sufficient to cause 

 the speedy action of chlorine on the other gases. The paper 

 -contains also directions for analyzing mixtures of hydrogen, car- 

 ;buretted hydrogen, and carbonic oxide, but these, from their 

 nature, are incapable of abridgment. 



By the analytical processes thus established, he proceeds to 

 examine the composition of oil gas and coal gas. The result}* 

 are given in tables, but the general issue of the experiments is 

 that oil gas (as he had formerly shown with respect to coal gas) 

 is very far from being uniform in composition, but differs 'greatly 

 in specific gravity and combustibility, when prepared at different 

 times even from the same kind of oil, owing to variations of 

 temperature and other circumstances. Essentially the gases 

 from oil and from coal are composed of the same ingredient^, 

 though in different proportions, viz. simple hydrogen, light car^ 

 buretted hydrogen, and carbonic oxide gases, with the addition 

 of variable proportions of an elastic fluid, which agrees with ole- 

 fiant gas in being condensible by chlorine, but consumes more 

 oxygen and gives more carbonic acid, by combustion, and has a 

 higher specific gravity than defiant gas, and even than atmo- 

 spheric air. Whether this ingredieijt be strictly a gas, perma- 

 nent at all temperatures, or a imxture of olefiant gas with some 

 new gas, constituted of hydrogen and charcoal in different pro- 

 portions from what are found in the known compounds of those 

 elements, or merely the vapour of a volatile oil, he leaves to be 

 decided by a future train of experiments. 



CAMBRIBGE PHILOSOPHICAL SOCIETY. 



Address read at the First Meding of the Cambridge Philosophicffl 

 Societi/, stating the Design and Objects of its Institulion i 

 written at the Request oj the Council^ by Ediuard JJaniel 

 C/arke, LL.D. Professor of Mineralogy in the University of 

 Cambridge, 6^'c. S)'C. 



At the opening of the first meeting of the Cambridge Philo- 

 sophical Society, the Members of the Council avail themselves 

 of the earliest opportunity that has been offered to them, of 

 expressing to the Society their congratulations upon its Institu- 

 tion. Convinced, as they all of them are, of the advantages 

 hkely to result from the establishment of sucIj a Society, they 

 do not hesitate to declare their opinion, that an event of movj^ 

 importance, as affecting the best interests of science, has rarely 

 occurred in the annals of the University. 



A century has now elapsed since the celebrated Woodwarft 

 prefixed the following axiom to his " Essay upon the Natural 

 History of the Earth," which took the lead in subjects of geolo- 

 gical inquiry. <^ From a long train of experience," said he. 



