238 REPORTS ON THE STATE OF SCIENCE. 



This, after washing with potash, distilled at 63°-7 at 745 mm. It was 

 a colourless liquid, specific gravity -69 at 18° -75, insoluble in water, 

 and unacted upon by acids. Boucbardat compared it with Reichenbach's 

 'eupion.' (6) By warming the original liquid to 12° -5 and condensing the 

 vapour in a freezing mixture a liquid was obtained boiling below 0° and 

 having a specific gravity '65 at — 5°. It was soluble in ether and alcohol. 

 On the addition of concentrated sulphuric acid it gave a brownish coloured 

 product, which was not acted upon by potash or hydrochloric acid. It 

 boiled at 85°'5 C. and had a specific gravity -SS at 15°'5. Bouchardat 

 considered it to be identical with Faraday's then recently discovered 

 hydrocarbon,' now known as benzene, (c) After the liquid boiling below 

 0° had been collected, a fraction was obtained boiling between 12°"5 and 

 22°"5. From this liquid, on cooling in a freezing mixture, a solid sepa- 

 rated in the form of fine white needles. These were separated from the 

 adhering liquid, and on examination Bouchardat found the substance to 

 be a hydrocarbon, to which he gave the name caoutchene. It forms a 

 white opaque mass, melting-point, — 12°'5 ; boiling-point, 18°"12 at 752 

 mm. ; specific gravity, -65 at — 2°'5 ; soluble in alcohol, and is not acted 

 upon by alkalies. 



Analysis gave the figures : — 



1. C = 85-09 per cent. H = 13-77 per cent, 



2. C = 85-44 „ ,; H = 14-59 „ „ 



The treatment of this subject, however, on modern scientific lines, and 

 the isolation of definite compounds from the distillation products of 

 rubber, may be said to date from 1860, when Greville Williams ^ con- 

 tinued the work of Himly and Bouchardat. Williams distilled the india- 

 rubber in an iron alembic, using the lowest temperatures consistent with 

 the distillation, and the process was stopped before all the heveene 

 fraction had passed over. The distillate possessed an unpleasant odour, 

 due, he considered, to the volatile bases resulting from the decomposition 

 of the vegetable casein in the rubber. By purification and redistillation 

 he separated two chief fractions from tlie oil, (1) boiling at 37°-44°C., and 

 (2) boiling at 170°-180°C. These same fractions appear to have been 

 also isolated about the same time by Williams from the distillation pro- 

 duct of gutta-percha. 



Isojjrene. 



No. 1, after careful rectification over sodium, boiled almost entirely 

 between 37° and 38°. It had a vapour density of 2*44 (air=l) (cal- 

 culated for C5H8=2'45), and specific gravity -6823. The mean of three 

 analyses of the liquid obtained both from rubber and gutta-percha gave 

 the figures : — 



C = 88-0 H = 121 



Calculated for C^Hj 

 C = 88-2 Hzill-8 



He gave to this liquid the name ' isoprene.' Williams observed that 

 this isoprene, when left in a bottle for some months, became sticky, 

 lost its fluidity, and became 'ozonised' (peroxidised) by absorbing the 

 oxygen of the air. The pei'oxidised isoprene possessed marked bleaching 



' Phil. Trans. Boyal Soc, 1825. 



2 Proceedings Royal Society, 1860, p. 517. 



