288 On a Substance produced during 



aeid ; and that it had been found in the condensing vessel of 

 the coal-gas apparatus. I then paid no further attention to it 

 than slightly to examine its properties, and finding it not acid, 

 and insoluble in liquid ammonia, merely concluded that it was 

 not what it had been represented. 



Very lately, I am indebted to Mr. Jennings for a large supply 

 of what I consider to be the same product ; he informs me that 

 it is produced in considerable quantities in the first and second 

 distillation of coal tar ; that it gradually precipitates from the 

 oil, and that every hundred gallons deposit about five pounds 

 of it ; that the deposition is greatest in cold weather ; and that 

 it is consequently probable that the oil, even when highly rec- 

 tified, retains a portion of it in solution. 



The substance, when freed from empyreumatic oil, is inodor- 

 ous and insipid ; it is extremely volatile, and fusible at a tem- 

 perature a little below that of boiling water. Its vapour con- 

 denses in brilliant needles, and plates;; the latter appearing 

 hexaedral, and often perfectly transparent. After fusion, it 

 concretes with much expansion, on cooling, into a soft fibrous 

 crystalline mass, of a specific gravity little exceeding that of 

 water. It is highly inflammable, and during combustion throws 

 off a very remarkable quantity of carbonaceous matter. It is 

 insoluble in water. 



Alcohol sp. gr. 820, readily dissolves this substance, and 

 acquires an acrid and aromatic flavour. The solution is decom- 

 posed by water, and a milky mixture results. Hot alcohol 

 appears to dissolve it in any quantity ; and a» the solution cools, 

 it is deposited in beautiful crystalline flakes. 



Sulphuric ether, at common temperature, also dissolves it in 

 large quantities ; and fine crystals are separated during the 

 spontaneous evaporation of the solvent. 



In chlorine, this substance fuses spontaneously, and evolves 

 fumes of muriatic acid ; the gas is absorbed with the production 

 of heat, and a compound results, apparently analogous to that 

 obtained by the mutual action of chlorine and defiant gas. 

 Intensely heated in chlorine, it deposits charcoal, but does not 

 burn. 



