222 



idea naturally suggested itself of examining this substance in com- 

 parison with the products of artificial destructive distillation. 



With this view, one of us* was induced to procure, through the 

 intervention of a friend, several tons of Rangoon tar, which was care- 

 fully collected at the source, and transmitted to Europe in well-secured 

 vessels. Our experience in the course of this inquiry, has shown 

 that this quantity, large as it may appear, was by no means too 

 ample a supply. Burmese naphtha contains indeed so great a variety 

 of substances, and some of them in so exceedingly minute a propor- 

 tion, that even the large amount of material at our disposal was in- 

 sufficient for the complete examination of several constituents, the 

 presence of which we had succeeded in establishing beyond a doubt. 

 As an example, we may state that Burmese naphtha contains small 

 quantities of organic bases, the study of which we were compelled to 

 postpone to a later period, when an additional quantity of material, 

 which is now on its way to Europe, will have come to hand. 



We have already mentioned that Rangoon tar is almost entirely 

 volatile, and preliminary experiments proved to us that the distilla- 

 tion could be effected most conveniently, and with less danger of ob- 

 taining products of decomposition, in a current of steam ; first of a 

 temperature of 100 C. (212 F.), and subsequently of steam super- 

 heated by passing, before it entered the still, through a system of 

 pipes the temperature of which could be regulated. Treated in this 

 way, it furnishes 96 per cent, of volatile products, fluid and solid. 



Steam of 100 C. (212 F.) carries over 11 per cent, of a volatile 

 oil perfectly free from solid hydrocarbons, which at that tempera- 

 ture are entirely retained in the distillatory apparatus. Between the 

 temperatures of 110 and 145 C. (230-293 F.), 10 per cent, of a 

 further distillate is obtained, which is almost free from solid hydro- 

 carbons. The temperature may be raised to 160 C. (320 F.) 

 without materially augmenting this per-centage ; but on gradually 

 increasing the temperature of the steam to the fusion-point of lead, 

 the operation yields 20 additional per cent, of distillate, which retains 

 its fluidity at C. (32 F.), notwithstanding the presence in it of an 

 appreciable quantity of solid matter. At this stage of the process 

 the products of distillation begin to solidify on cooling, and about 

 31 per cent, of a crystalline material is obtained sufficiently consistent 

 * Warren De la Rue. 



