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XIV. On the Potatoe Spirit Oil of the French Chemists. By 

 JAMES APJOHN, M.Z)., M.R.I.A., Professor of Chemistry in 

 the Royal College of Surgeons, Dublin*. 



TN December 1838, I received from my friend Mr. Scanlan 



a specimen of an oily fluid which had been given him by 

 Mr. Bowerbank, an eminent London rectifier, and which the 

 latter gentleman had found in small quantity in the faints or 

 weak spirit drawn off towards the close of the rectification of 

 common whisky. Shortly previous to this time, Mr. Coffey, 

 the inventor of the celebrated patent still, had observed the 

 same substance at the extensive distillery of Sir Felix Booth; 

 and upon coming over to Dublin, and visiting the establish- 

 ment of Mr. Busby at Blockpitts in this city, Mr. Scanlan had 

 the satisfaction of recognizing this same oil in the faint vessel, 

 constituting a thin stratum resting upon the surface of the re- 

 mainder of the fluid. 



The oil obtained from Mr. Busby's concern had a reddish- 

 brown colour, owing to dissolved vegetable matter, and its 

 specific gravity was '8401, that of the faints on which it rested 

 being '9269. Shaken in a graduated tube with an equal bulk 

 of water, its volume was reduced 20 per cent., and the water 

 upon distillation yielded alcohol. To insulate the oil, there- 

 fore, the following method was adopted. 



The fluid obtained from the faint receiver was first washed 

 with an equal bulk of water ; then shaken in a bottle with an 

 equal weight of pulverized and anhydrous carbonate of potash, 

 and finally distilled from a glass retort, the condensation be- 

 ing effected by Liebig's tube refrigeratory. It began to boil 

 at 262, after which the temperature rose gradually until it 

 became 268, at which it continued until the whole of the 

 oil was nearly over. The fluid first drawn off was set apart, as 

 still containing alcohol, and that alone reserved for further 

 purification which distilled over at 268. This portion was 

 redistilled. The ebullition commenced a little over 267, and 

 in less than a minute rose to 268, at which point it continued 

 until the rectification was nearly completed. The first and 

 last portions being rejected, the middle portion, or that which 

 came over at 268, was set apart for experiment. 



The oil thus procured is a perfectly colourless liquid, de- 

 stitute of all viscidity. The specific gravity is -8138, and, as 

 has been already observed, it boils steadily at 268; cooled 

 to 6 it does not congeal. With rectified spirit it is mis- 

 cible in all proportions, its specific gravity being thus aug- 



* Communicated by the Author. 



