320 SCIENCE PROGRESS 



of the primary products of decomposition and of products of 

 their interaction at relatively low temperatures. 



It contains a not inconsiderable proportion of saturated 

 hydrocarbons — in fact, of petroleum — together with unsaturated 

 hydrocarbons of the olefine and acetylene series and a relatively 

 small proportion of benzene and its homologues but no benzene- 

 like hydrocarbons of higher series. All these hydrocarbons 

 are most valuable solvent materials and may also be used in the 

 internal combustion engine. 



Phenols are present in far larger proportion than in ordinary 

 coal tar, particularly the higher homologues of phenol. But 

 little ammonia is produced during the distillation and basic 

 substances appear to be less abundant than in gas tar. 



To account for the presence of paraffins and unsaturated non- 

 benzenoid hydrocarbons, it must be supposed that coal contains 

 a very considerable quantity of " fatty matter " of some kind, 

 as such matters are known to yield petroleum hydrocarbons on 

 distillation. I am inclined to think that the benzenes are mainly 

 synthetic products, formed by processes akin to those by which 

 such hydrocarbons are produced in the manufacture of oil gas. 

 The proportion in which the various homologues of benzene 

 are present appears to be somewhat different from those in 

 which they occur in ordinary coal tar. It is to be supposed 

 that the phenols are derived directly from hydroxy-benzenoid 

 compounds in the coal and it will be a matter of considerable 

 interest to establish their nature. The greater proportion of 

 benzenes in ordinary coal tar is probably due to the conversion 

 of the phenols in large part into benzenes by the action of 

 heated carbon. 



The gas given off during the coking process is very rich. 

 In the first place, I would advocate that this gas be substituted 

 for the rubbish now produced by carbonising coal at very high 

 temperatures so as to obtain the maximum possible yield of 

 gas. It is absurd — no other expression is suitable — that the 

 production of gas from coal in this manner should constitute 

 a primary industry, especially as the coke which is produced 

 is not suitable for ordinary domestic use. 



It is time that the public realised that the article now sup- 

 plied is beneath contempt and that a better article is at hand and 

 can easily be supplied. Great improvements are in sight in the 

 application of gas to heating purposes and it is to be expected 



