55 



them. At present the Kimmeridge oil question rests in the phase 

 of research into the nature of the class of sulphur compounds that 

 up to the present have prevented the adequate use of the shales. 



In the refining of shale oils two different methods may be 

 adopted : either the treatment of the oil after distillation or the 

 treatment of the shale in the process of retorting. Numerous 

 attempts have been made on Kimmeridge shale according to both 

 methods, but so far no process has been devised to work on a 

 manufacturing scale, though many encouraging and instructive 

 results have been obtained. Several patents for the treatment of 

 Kimmeridge shale have been taken out, of which three of the 

 oldest will be briefly mentioned. The British patent 1882/3792 by 

 E. K. Mitting uses superheated steam while retorting the shale, 

 with the object of increasing the yield of ammonia and removing 

 the pyridine which had been identified in Kimmeridge oils as early 

 as 1854 by Williams. Another patent 1883/3725 by C. M. Irvine 

 and R. Slater brings out nothing new and only claims to get the 

 sulphur out of the noxious gases of the distillation by burning 

 part and combining the S thus obtained with the H^S in the 

 gases, so bringing about the liberation of the sulphur. The third 

 patent by R. Irvine 1884/5933 is a very interesting one. Taking 

 the point of view that sulphur easily destroys paraffin wax (crack- 

 ing it and combining with the fragments and evolving H^S — ) and 

 that, therefore, Scotch shales, especially the poorest in sulphur, 

 yield the greatest amount of paraffin wax and Kimmeridge shale 

 little or none, he advocates the use of ammonia in the gaseous form 

 or as the carbonate during the process of distillation for the pur- 

 pose of increasing the yield of wax. The use of ammonia at high 

 temperatures to desulphurise sulphur-laden o ; ls constitutes the 

 main idea of one of the more successful attempts of quite 

 recent date, mentioned by Dr. F. M. Perkin (Inst : Petr : Techn : 

 Vol. III., p. 238). 



While working with sulphur-containing o ; ls of nearly any 

 description one fact of interest is noticed: H-*S is always evolved 

 during the distillation. One would at first think that when this gas 

 escapes it signifies that sulphur is escaping from the oil and that 

 we have only to augment the rate of evolution of H' 2 S to solve 

 the problem. This would be the case if it were not for the fact that 

 the amount of hydrocarbons escaping simultaneously as permanent 

 gas or uncondensible vapour remains in proportion, and conse- 

 quently the percentage of sulphur in the gases is practically the 

 same as in the oil and no improvement is obtained. It is, how- 

 ever, possible that here is the clue to the problem. As far as the 

 research on Kimmeridge shale is concerned hundreds of experi- 

 ments with all kinds of chemical treatment have been recently 

 made, but without success. In some cases the oercentage of 

 sulphur has been brought down considerably, but' the processes 

 are too^ expensive for industrial application. 



It is a well-known fact that by a suitably adapted hydro- 



