III. On a New Combustible Gas. By THOMAS THOMSON, M. D. 

 F R. S. Lond. & Edin. Professor of Chemistry in the 

 University of Glasgow. 



(Read April 16. 1827J 



AT has been generally known for several years, that, when the 

 acetic acid formed by the distillation of wood is rectified, there 

 is obtained a transparent spirituous liquor, analogous in many re- 

 spects to alcohol, though very different in others. This liquid 

 has received the name of pyroxylic spirit. It is manufactured 

 by Messrs TURNBULL and RAMSAY of Glasgow. I have been in 

 the habit for several years of employing it for combustion in 

 lamps instead of alcohol. It is a good deal cheaper, and raises 

 just as good a heat as alcohol ; for I can make the smah 1 plati- 

 num crucible, which I use for drying the products of analysis, 

 red-hot by means of a pyroxylic spirit lamp in a few minutes. 



Pyroxylic spirit is as limpid and colourless as alcohol. Its 

 specific gravity, when well rectified, is O812. It has an agree- 

 able smell, not, however, quite free from that of naphtha. Its 

 taste is very disagreeable, owing, I believe, to a small portion of 

 naphtha, or empyreumatic oil, which it holds in solution, and 

 from which we cannot free it by any known process. A set of 

 experiments on pyroxylic spirit by Messrs MACAIRE and MAR- 

 CET was published in the Bibliotheque Universelle for October 

 1 823. These gentlemen have described several of its properties, 

 and subjected it to an analysis, from which it appears that, like 

 alcohol, it is composed of hydrogen, carbon and oxygen, though 

 the atomic proportions are different. 



My object, in this short paper, is to give an account of a new 

 gaseous substance which I accidentally obtained about a year 



