of certain iii^ammalle gaseous Compounds. 201 



from the Company's works in Westminster, and the oil gas fur- 

 nished bv the decomposition of common whale oil, in an appa- 

 ratus erected for that purpose bv Messrs. Taylors and Marti- 

 neau, at Apothecarie;-;' Hall*. These gases have been submit- 

 ted to analysis by different chemists of eminence ; and we are 

 more especially indebted to Dr. Henry for a series of valuable 

 researches respecting their production and compositionf. It is 

 therefore with considerable diffidence that I venture to propose 

 views relating to them in many respects different from those of 

 niv predecessors in this important branch of chemical inquiry. 



It is generally admitted, that there are two definite compounds 

 of carbon and hydrogen ; the one, usually termed olejiant gas, 

 consisting of one proportional of carbon and owe of hydrogen ; 

 and the other called light liydrocar buret, composed of one pro- 

 portional of carbon and tivo of hydrogen : the former of tliese 

 gases appears to have been discovered in 1796, by the associat- 

 ed Dutch chemists, Messrs. Bondt, Dieman, Van Troostwick, 

 and LawerenbourgJ, and the other first examined by Mr. Dal- 

 ton§. Assuming hydrogen as l,the specific gravity of olefi- 

 ant gas is 13,4 ; and it contains 1 proportional of carbon =5,7 

 -)- 1 proportional of hydrogen =1. Light hydrocarburet has 

 generally been considered as consisting of 1 proportional of car- 

 bon = 5,7 + 2 proportionals of hydrogen =2, and its specific gra- 

 vity has been stated as 7,7 compared with hydrogen ; or as 

 57'365, assuming atmospheric air as 1. 



My first object in theeNamination of coal gas was to ascertain 

 its specific gravity ; and I was surprised to find the first that I 

 examined so low as ,4430. There was some variation in differ- 

 ent specimens ; and the specific gravity of that prepared in the 

 laboratory of the Royal Institution, and purified in the usual way 

 by condensation in cold vessels, and passing through lime water, 

 was as high as ,4940, which is the heaviest that 1 have yet met 

 with. 



Having been led to consider coal gas as consisting essentially 

 of the two varieties of carburetted hydrogen, 1 imagined that the 

 specific gravity of the light hydrocarburet must have been esti- 

 mated too high ; I therefore prepared liglit hydrocarburet from 

 acetate of potash, and having se})arated its carbonic acid bv 

 lime, found its specific gravity ,6H7 ; the specific gravity of the 

 gas from stagnant water, according to Mr. Dalton||, is ,600, 



* A description and plate of this itpparatus are given in the Quarterly 

 Journal of Sciences, &c. Vol. VIII. p. ['JO. 



t Nicholson's Journal, Vol. XI. p. (J5. I'hilos. Trans. 180S. Manches- 

 ter .Memoirs, Vol. III. New Series. Phil. Mag. Vol. XXXII. p. 277. 



J Jtmrnal (h P/iygiqut; XI V. § New System of Chemical Philosopiiy. 



II New System of Chemical Philosophy. 



Vol. :>6. No. 269. Sept. 1820. C c and 



