122 ON A PROCESS OF FRACTIONAL CONDENSATION. 



1. Warren de la Rue and Hugo Muller,* in their paper entitled u Chemical Examina- 

 tion of Burmese Naphtha or Rangoon Tar/' after detailing the preliminary treatment 

 by distillation in a current of steam, add that "A further separation of the various 

 products was effected by repeated fractional distillations ; but no absolutely constant 

 boiling-points could be obtained, notwithstanding the great number of distillations 

 and the large quantity of material at command. It is true that considerable portions 

 of distillates could be collected between certain ranges of temperature, tending to 

 indicate a constant boiling-point j nevertheless it soon became evident that distillation 



could not effect the separations of the 



and that 



must be had to other processes." The other processes resorted to were, treatment 

 with sulphuric and nitric acids, either separately or mixed ; but still with very imper- 

 fect results. This acid treatment, which was first proposed by De la Rue, and sub- 

 sequently employed by C. Greville Williams/)- Schorlemmer, and others, will be further 

 noticed below. 



2. Frankland, ;f in speaking of a mixture of the hydrocarbons of the formula} 

 C n H n and C n H n + 1 (now generally considered as C n H n . A which have a difference of 



6° to 7° C. between their boiling-points, says, « The separation of two such bodies by 

 distillation alone is impossible " ; and suggests that the employment of anhydrous 

 ulphuric acid may accomplish the object by dissolving out the body of the formula 



C n H n 



he also had 



3. And so recently as 1862, Sehorlemmer,§ in his first paper "On the Hydrides of 

 the Alcohol-Radicals existing in the Products of the Destructive Distillation of Cannel 

 Coal," remarks that « it was, however, found impossible to obtain a product of con- 

 stant boiling-point by repeated fractional distillations " ; and 

 the acid-treatment above referred to. 



4. Pebnl, 1 1 after an elaborate research on the petroleum from Galicia, in which 

 Wurtz's bulbs were employed, and also Eisenstuck^ who made an extended investiga- 



* Proceedings of the Royal Society, VIII. 221. 



t Philosophical Transactions, 1857, 447. 



t Quarterly Journal of the Chemical Society, 1851, 3, 43. 



§ Journal of the Chemical Society, XV. 419. 



Annalen 



irte Destillationen zu entwirren." 

 f Annalen der Chemie und Pharm 



'S 



Twnw, a a- c • • ^ ^ Aiai - ^y, says as follows : — " Mit den 5° zu 5° aufgesammelten 



Destdlaten wurde die fractionirte Destination wk»Am. — w ^ 



siphon Wn,h. •♦ * *a ™J esimatlon ™der von Neuem vorgenommen, aber nachdem diese Operation 

 sieben Wochen mit etwas 50 Pfnnd *stf>;™i e 1 o > r 



constant™ K A Z iT f ^rtgesetzt worden war, erhielt ich doch kein Product von irgend 



constantem 



