134 



ON A PROCESS OF FRACTIONAL CONDENSATION. 



But in my investigations, I have undertaken to prove the negative as well as the 

 positive. I have attempted to carry the process of separation so far, that I might 



■k 



the absence of other bodies, as well as the presence of those obtained ; and 

 g up of the intermediate fractions has generally been the most tedious part of 



I have continued to 



become distributed in regular 



op 



upon these by themselves, until they also have 



no 



bodies app 



among 



frac 



year 



tions of constant boiling-point, or to such an extent that the intermediate quantiti 

 have become too small to admit of further continuance of the process. 



This process has been in constant use in my laboratory during the last three 

 In this time it has been applied in the study of petroleums, coal oils, the more volatile 

 parts of coal- and wood-tars, the essential oil of cumin, commercial fusel oil, from corn 

 whiskey, and even to mixtures more complex than either of these. As the result of 

 this long experience, I can say that as regards bodies not decomposed by heat in dis- 

 tillation, I have not yet found a mixture so complex that it may not be resolved by 

 this process into its proximate constituents so completely, that these shall have almost 



absolutely constant boiling-points 

 have obtained these 



In 



peated 



from petroleums, I 



pure, that the contents of an ordinary tubulated 



charged with one of them has been completely distilled off without any 



tial change of temperature : i. e., not to the amount 



quently remaining absolutely constant 

 boiling-point not exceeded by that of distilled 



of J° C, the thermometer fre- 

 for more than half an hour, a constancy of 



This state of purity, I think I 



may safely assert, has never before been attained from such mixtures by any system 

 of fractional distillation. 



^ As I shall soon be prepared to present to the Academy detailed results of the inves- 

 tigations above referred to, I may omit further allusion to them on this occasion. 



I would remark, in conclusion, that it seems to me not improbable that this process 

 may ultimately prove to be of great value in the arts. It is not too much to anticipate 

 that, whenever the various constituents of the mixtures referred to shall have been 

 separately and thoroughly studied in a pure state, some of them may be found to pos- 

 sess properties which will give to them great commercial value, sufficient to justify the 

 expenditure necessary to separate them in large quantities. 



