ON XnP: PRESENT POSITION OF THK CHEMISTRY OF RURKER. 235 



transparent, until at a specific gravity about •680 it was jierfectly 

 colourless and highly volatile. In the specification Barnard also gives 

 practical instructions for the distillation, the cleaning out of the still by 

 means of solder, and the removal of the obnoxious odour from the oil. 

 The oil was used as a solvent for caoutchouc, resins, varnishes, and paints, 

 and for mixing with cocoanut oil to render it suitable for burning in 

 lamps. No delinite boiling-point was given, so it must be presumed that 

 the term caoutchoucine included all the lighter and lower boiling portions 

 of the oil. 



In 1834 Beale and Enderby ' prepared the oil in large quantity. 

 They are stated to ha^e obtained by the distillation of rubber 83^ per 

 cent, of an oil of specific gravity "640 and boiling below 38° C. Thir, 

 statement occurs iu ' L'Institut,' 1834, and was copied from there into the 

 ' Jahresberichte ' of Berzelius, xv. 320 (1836). The process here referred 

 to may be the one for which Barnard was granted a patent in 1833, 

 particularly as he was working at the works of Messrs. Enderby. The 

 yield of the liglit oil, however, is obviously erroneous. 



In 1834 J. T. Beale, of Wliitechapel, obtained a patent for a new 

 form of lamp (Specification No. 6537), in which it was proposed to burn 

 ' liquids, including any of the fluids of the distillation and occasional 

 rectification of indiarubber.' 



The oil caoutchoucine was analysed quantitatively by Dumas, who 

 found it to be composed of carbon and hydrogen in the proportions 

 C =88 per cent., H=12 per cent. In the 'Annalen de Chimie u. 

 Pharm.' for 1835, Liebig, in an article entitled 'A Note concerning the 

 Purification of Products obtained by the Dry Distillation of Organic 

 Materials,' describes an oil which ' Dr. Gregory had obtained in large 

 quantity by the distillation of rubber.' Liebig states that on rectification 

 the boiling-point of the oil rose slowly from 35° to 65°, that the specific 

 gravity was "673, and was composed of carbon and hydrogen only. The oil, 

 distilling at 36°, reduced sulphuric acid with the evolution of sulphur 

 dioxide and the formation of black colour. On afterwards adding water 

 to the product of the acid treatment, an oil was obtained which, after 

 rectification, boiled at 220°. 



In 1836 Gregory '^ published his own investigations in an article 

 entitled ' Concerning a Volatile Oil obtained from Indiarubber by De- 

 structive Distillation, with Notes concerning some other Erapyreumatic 

 Substances.' 



By repeated rectification Gregory obtained liquids, boiling from about 

 32° C. (not constant) to 77° C, which had a specific gravity of •666 at 

 15°^5. He found that this product was not identical with an oil known as 

 ' eupion,' previously described by Reichenbach,^ as it was at once de- 

 stroyed by sulphuric acid. Gregory also isolated from the distillate the 

 fractions mentioned by Liebig, the figures varying slightly, however, 

 from those given by the latter chemist. He stated that he obtained a 

 highly rectified oil boiling at 96° F. (35-5° C), specific gravity •670, which 

 on treatment with sulphuric acid yielded an oil, boiling-point 220°, and 

 which had the same composition as oil of turpentine (C5H8 or CoHig). 

 Some of the oils obtained boiled as high as 360° C. 



*o'^ 



• L'lnstitut, 1834, p. 290. 



'^ London and Edinburgh Pliil. Mag. and Journ. of Scinnce, Third Scries, vol. ix. 

 (1836), p. 322. 



' Ann. de Pharm., 8, 217 (1833). 



