282 REPORTS ON THE STATE OF SCIENCE, ETC. 



combine it with some preliminary wasliing process in order to reduce the ash 

 content of the semi-coke. 



Supposing that further technical developments result in the establishment 

 of a low temperature carbonisation industry for the manufacture of a smoke- 

 less domestic fuel, it is of interest now to forecast the effect of such develop- 

 ments upon the future home supplies of motor spirit and fuel oils. It 

 may be provisionally assumed that the amount of coal which could be so 

 carbonised to supply domestic fuel requirements would be at least 40 (and 

 possibly even 50) million tons per annum. Taking the former of these two 

 figures, this would mean a possible production of about 100 million gallons 

 (or about 350,000 tons) of motor spirit, and 600 million gallons (or about 

 2,750,000 tons) of anhydrous tars (fuel oils). 



Present Tendencies in the Use of OH Fuel. — Before the advent of the 

 internal combustion engine, the term ' fuel oil ' was restricted to an oil intended 

 to be burnt in furnaces and the like. In the early days of oil fuel practice, 

 comparatively light oils were used. They were ' atomised ' and injected into 

 the boiler furnace or the like by means of steam or air, and the burners used 

 were often of a crude and unsatisfactory character. In recent years, however, 

 more attention has been given to the proper design of such burners, and to 

 the more effective combustion of the fuel oil. The consumption of air or steam 

 by the oil burners has been considerably reduced, and, as they have attained 

 a higher degree of mechanical efficiency, heavier oils have been successfully used 

 in them. Methods have now been devised whereby heavy oils may be sprayed 

 into the furnace under pressure alone, without the aid of either steam or air; 

 and, therefore, it has become possible for heavy petroleum residues, such as 

 asphaltum, to be employed as first-class fuels for land installations. A similar 

 tendency has recently been manifested in the use of fuel oil in internal com- 

 bustion engines. Until quite recently petroleum refiners prepared a very light 

 fuel oil for these engines, but mechanical research is now being directed in 

 order to render them capable of burning even the heaviest oils. Progress 

 in this direction has been greatly helped by scientific investigations upon 

 the spontaneous ignition temperatures of fuel oils. The outstanding question 

 to-day is how to adapt a heavy fuel oil for use in low compression internal 

 combustion engines; this is now receiving the close attention of scientific 

 investigators, and it may be hoped that as a result of their work the public 

 will in due course be enabled to use heavy fuel oil in the place of motor spirit. 



III. The Chemistry of Coal, 



Progress towards the solution of the problem of the constitution of coal 

 substance can be recorded, notwithstanding the magnitude and complexity of 

 the problem. The difficulties arise in no small measure from the absence from 

 the products of such researches of bodies with crystalline habit or other well- 

 defined physical characters by which the chemist is accustomed to identify the 

 compounds he isolates. Still, the literature shows the subject has attractions for 

 not a few chemists who, employing various methods of attack, seek to obtain in- 

 formation as to the nature of the multifarious compounds which go to the 

 make-up of coal. As, however, different investigators select for their study 

 coals of varying origin and of different classes, it is not always easy to compare 

 the results obtained. 



The work of Clark and Wheeler {Trans. CJiem. Soc. 1913. 103. p. 1704), 

 combining the application of solvents with the study of the action of heat 

 upon the extracts of the coal so obtained, has undoubtedly given much useful 

 and valuable information. The results, however, still leave open to conjecture 

 and theoretical explanation the true nature of the components of the several 

 fractions. The classification of the coal components by Clark and Wheeler based 

 upon the pyridine-chloroform treatment is too facile"; nor could it be expected 

 to provide material for a complete explanation of the properties of coal. 



The breaking down of a bituminous coal by treatment with a mixture of 

 pyridine and amyl alcohol yields an extract from which, by successive use of 

 ether and light petroleum. Bone, Pearson, Sinkinson, and Stockings {Proc. Roy. 

 iioc, A, vol. 100, 1922, p. 582) have succeedea in obtaining (1) a non-resinous 

 wax-like substance, (2) a resin, to which the formula C31H32O3 is assigned, 



