514 Royal Society : — 



solid product into at least two distinct compounds, which appear to 

 have the same per-centage composition, agreeing either with C^ H^ or 

 Cn Hn+„ but which differ from each other in their physical properties. 

 By the action first of sulphuric acid saturated with anhydrous acid, 

 then with anhydrous sulphuric acid itself, we believe that we shall 

 obtain compounds which will enable us to determine a rational for- 

 mula for each of these interesting bodies. 



Liquid Constituents. 



In order to purify the liquid constituents of Burmese naphtha, they 

 were, after the separation of the solid portion from such as contained 

 any, twice redistilled in a current of steam, first of 100° C. (212° F.), 

 and subsequently of superheated steam, the temperature of which 

 was gradually raised. In the redistillation, however, steam of only 

 100° C. (212° F.) was found to carry over fluids which boiled at a 

 temperature as high as 300° C. (572° F.). 



A further separation of the variovis products was effected by 

 repeated fractional distillations ; but no absolutely constant boiling- 

 points could be obtained, notwithstanding the great number of distil- 

 lations and the large quantity of material at command. It is true 

 that considerable portions of distillates could be collected between 

 certain ranges of temperature, tending to indicate a constant boiling- 

 point ; nevertheless it soon became evident that distillation alone 

 could not effect the separation of the various constituents, and that 

 recourse must be had to other processes. The employment of con- 

 centrated sulphuric acid first suggested itself, and by its means a 

 whole group of hydrocarbons could be removed from the distillates, 

 the residue consisting of hydrocarbons, on which it had no action. 

 This was an important step ; but recourse was subsequently had, 

 with even more success, to the action of strong nitric or a mixture of 

 nitric and sulphuric acids, by which means a series of nitro-compounds 

 were obtained, which presented the advantage of being more easily 

 studied than the sulpho-acids. The nitric-acid method, which has 

 already been described at some length*, promises to be of general 

 applicability in the separation of complex mixtures of hydrocarbons, 

 and has, in the hands of Mr. C. Greville Williamsf, been lately em- 

 ployed with advantage in the investigation of " Some of the products 

 of the distillation of Boghead Coal at low temperatures." 



Hydrocarbons separable by Sulphuric Acid and Nitric Acid. 

 The proportion of hydrocarbons removeable from the various distil- 

 lates by means of concentrated sulphuric acid, nitric acid, or a mix- 

 ture of both acids, is in most cases small when compared with the 

 part not acted upon ; it increases generally, however, with the boiling- 

 point of the fluid, varying from less than one-tenth to nearly one-third 

 part of the original compound-hydrocarbon. The nitro-compounds 



* In the specification of a patent granted to Warren De La Rue, Dec. 23, 

 1854, and entitled " Improvements in treating products arising from the distilla- 

 tion of a certain Tar or Naphtha, to render the same suitable for dissolving or 

 removing Fatty or Resinous Substances." 



t Phil. Mag. S. 4. vol. xiii. p. 134. 



