236 REPORTS ON THE STATE OF SCIENCE. 



On October 14, 1834, John Dal ton read a paper before the Manchester 

 Literary and Philosophical Society ' Concerning certain Liquids obtained 

 from Caoutchouc by Dry Distillation.' The paper did not appear in 

 print, and it was not until 1836 that the contents of the paper were 

 published.' The liquids (contained in four phials) examined liy Dalton 

 had been submitted to him by an unknown friend, and he believed them 

 to be the results of successive distillations. 



No. 1 contained a dark coloured liquid, specific gravity -86. 



No. 2 contained a slightly coloured liquid, specific gravity -837, boiling-point 

 143°-166°. 



No. 3 contained a colourless liquid, specific gravity -752, boiling-point 60". 

 No. 4 contained a liquid, specific gravity -68, boiling-point 42°. 



He found that the vapour tension of No. 4 was practically the same 

 as that of sulphuric ether. Their relative volatilities were examined by 

 plunging the bulbs of thermometers into the liquids, and then observing 

 the fall of temperature on evaporation. He determined the specific 

 gravity of No. 4, and found it to be 2-07 (air=l). Dalton considered 

 that the oil No. 4 was identical with that obtained by Faraday by the 

 decomposition of oils by heat, but also that it was capable of further 

 rectification. 



A. F. C. Himly, in 1835, published his dissertation (Gottingen) 

 entitled ' De caoutchouc ejusque distillationis siccae productis et ex his 

 de caoutchine, novo corpore ex hydrogenio et carboneo composito,' ^ and 

 seems to have gone very fully into the question of tlie decomposition 

 products of indiarubber. He obtained on distillation of speck rubber 

 75 per cent, of an ethereal oily distillate of specific gravity -8702, and 

 from this he separated a portion boiling 56° to 96° C, which, when 

 carefully redistilled, gave a very volatile oil having the following proper- 

 ties : specific gravity, -654 ; boiling-point, 33°-44° C. It was completely 

 transparent, and had a pleasant odour, was not solidified at a temperature 

 of — 39°, and on evaporating on the bulb of a thermometer reduced the 

 temperature from +20° to —10°. This oil was named ' Faradayin ' by 

 Himly, because it possessed great similarity to an ethereal liquid ob- 

 tained about that time by Faraday by the distillation of an oil, although 

 the boiling-point of Faraday's liquid was 10° higher than that obtained 

 by Himly. Among other fractions obtained by Himly was one boiling 

 171°-5, to which he gave the name ' caoutchine.' By redistillation of this he 

 obtained a liquid, boiling-point 168° — 171°, which he purified as follows : 

 It was first dried with calcium chloride, and converted into caoutchine 

 hydrochloride by passing dry hydrogen chloride gas into the well-cooled 

 liquid. The product was dissolved in alcohol and reprecipitated with 

 water, dried with CaClj, and the hydrochloric acid split off by distilling 

 over quicklime or barium oxide, the resulting liquid being distilled over 

 potassium. The hydrocarbon thus obtained had the following properties : 

 It was a clear neutral oil, only slightly refractive, and possessed an odour 

 and taste resembling those of orange oil ; specific gravity, -8423 at 16° ; 

 boiling-point, 171° 5 at 750 mm.; did not solidify at —39°, and was 

 soluble in absolute alcohol, ethereal and fatty oils, and carbon disulphide. 



' London and Edinburgh Phil. Mag. and Joiirn. nf Science, Third Series, vol. ix. 

 183fi), p. 479. 



"^ Ann. d. Ch. u. Pharm. 27, 41. 



