120 Professor Christison on the Chemical Examination of 



lamp, and then by a third distillation from the vapour-bath, is 

 limpid and colourless, like sulphuric ether, and its density is 779. 

 From the trials I have made, I consider that the Rangoon pe- 

 troleum, when distilled on the large scale, will yield nearly a 

 third of its volume of this colourless naphtha. 



I need scarcely observe, that, in eastern countries, where the 

 fresh juice of the caoutchouc tree cannot be procured, the naph- 

 tha from the Rangoon petroleum may prove a useful article. 

 Like other kinds of naphtha it freely dissolves, or rather softens, 

 caoutchouc ; which, after the evaporation of the solvent, is reco- 

 vered with its original properties. When it is to be used for this 

 purpose, however, it must be carefully separated by distillation 

 from the crystalline matter I am presently to describe, which rises 

 as the distillation advances, and gives the naphtha a yellow co- 

 lour. For, if any material proportion of this impurity be pre- 

 sent, the caoutchouc solution dries very slowly, and long retains a 

 greasy surface. 



The yellowish, concrete, crystalline matter, like the petro- 

 leum itself, is not acted on by the caustic alkalies, or by the 

 strong acids. Alcohol dissolves it very sparingly ; ether and the 

 essential oils, freely and entirely. None of these solvents, there- 

 fore, is of any use for separating the crystalline matter from the 

 mass. But T have succeeded in procuring it in a state of purity 

 by the following process : 



The mass being cooled down to about 40° Fahr. it was spread 

 out on filtering paper, and then subjected to strong pressure be- 

 tween many folds of common blotting paper. In this manner, an 

 oily-like matter was taken up by the paper, and a pale yellowish- 

 white crystalline substance was left, which was subsequently de- 

 prived of its remaining colour by repeated solution in boiling 

 ether and recrystallization. Ether dissolved it largely, forming a 

 pale yellow solution, which, on being cooled by immersing the 

 vessel in very cold water, became a soft mass of interwoven crys- 

 tals. This mass was then taken out, spread quickly on filtering 



