B.— CHEMISTRY. 59 



as the chemistry of petroleum is concerned this is at present mere surmise, 

 which must be investigated as soon as practicable. The view is, however, 

 rendered plausible by the work which has been carried out at the Imperial 

 College during the past five years, which shows conclusively that the 

 formation and stability of ring systems depend on the character of the 

 groups attached to the carbon atoms forming the rings, and are not merely 

 dependent, as Baeyer supposed, on the tetrahedral angle of the carbon 

 atoms involved. It is probable also that a similar explanation may account 

 for the ' naphthenes,' and will provide a general explanation of polymerisa- 

 tion and depolymerisation upon which it will be possible to base improved 

 technical processes. 



The composition of petroleums varies in accordance with their origin. 

 Some are rich in aromatic hydrocarbons, and some are practically sulphur 

 free ; others contain so much of the last-named element as to render them 

 unfit for use. The Kimmeridge shale oils are instances of the latter type, 

 although doubtless if it were a paying proposition the sulphur could be 

 readily eliminated from these products. The oil from the Persian, 

 Mexican, and Ohio fields contains sulphur, which has to be eliminated 

 during the process of refining. Among the sulphur compounds present 

 mercaptans and thioethers have been identified, although whether they 

 are present in the crude oil as such or whether they are formed during 

 the refining process is still an open question. Their removal by washing 

 with liquid SO.^, an operation which is now carried out on a very large 

 scale at the refineries at Skewen, is of interest. 



It is clear, therefore, that the need for systematic research into the 

 character of petroleum products is urgent, and it is gratifying to note 

 that the Anglo-Persian Oil Company has established a research laboratory 

 at Sunbury-on-Thames, in which the important principles underlying the 

 industry have been and will be studied. 



Dyestuffs and Intermediates. 



Prior to the war Germany manufactured three-fourths of the dyestuffs 

 required for the world's markets. Of the remaining one-fourth, one-half 

 was made from German intermediates and was, therefore, dependent on 

 Germany. Switzerland, although without a domestic source of raw 

 materials, ranked second with about 7 per cent, of the world's production. 

 Great Britain produced about one-tenth of her requirements, and France 

 produced in French-owned and operated plants from 10 to 15 per cent, 

 of her cousiimption. In order to meet the patent requirements of France 

 and Great Britain, German manufacturers operated plants in those 

 countries where the final assembling operations were completed. The 

 small dye industry of the United States was almost entirely dependent 

 upon German intermediates. At the present time Great Britain produces 

 80 per cent, of the dyestuffs required for our own use, and we are, therefore, 

 in a position to review the conditions which have led to this remarkable 

 change and to consider the procedure necessary to strengthen it. It 

 cannot be said that any fundamental advance in the chemistry of the 

 dyestuffs has been made since Bohn discovered indanthrene in 1901, 

 although great advances have been made since then in the preparation of 

 new colours belonging to this and other known series. Consequently the 



