736 Prof. H. E. ArMnstrong on Low-Temperature Research 



extraordinarv and so unexpected that it may fairly be anticipated 

 that this will outweigh in importance all previous applications. 



The period being that during which the value of extreme exhaus- 

 tion has been brought into such special prominence, as the Institution 

 was the fountain-head of the means of attaining the highest vacua bj 

 means of refrigerated charcoal, I propose to term it the High Vacuum 

 Period. 



The Fullerian Professorship. 



The period is also noteworthy as that in which Sir James Dewar's 

 tenure of the Fullerian Professorship of Chemistry has exceeded in 

 length that of Faraday. Faraday was elected in 1833, Mr. Fuller 

 having founded the Professorship in the earlier part of the year ; 

 the salary attached to the post was only about lOOZ. a year. Faraday 

 was appointed for life, with the privilege of giving no lectures ; he 

 held the office until 1867 ; he was succeeded by Professor Odling 

 (1868-73) and Dr. J. H. Gladstone (1874-77). Sir James Dewar 

 came into office in 1877. 



The work done by Faraday has been described and discussed on 

 many occasions. Though mainly physical and entirely so during the 

 later period of his activity, during the earlier period it was largely 

 chemical : probably this side of his activity and the formative in- 

 fluence of the experience on his character is far too little appreciated ; 

 it was fraught with the most important consequences. The founda- 

 tion stone of the Dyestuff Industry, which has loomed so large in 

 the public eye of late, was laid by his discovery in 1824 of bicarduret 

 of hydrogen or benzol (now benzene), as it was termed later on, by 

 Liebig, when Mitscherlich, in 1833, prepared it from benzoic acid.'"' 



* In the latest edition of his " Coal-Tar and Ammonia " (5th edition, 1916^ 

 i. p. 223), Lunge makes the claim, that Faraday was anticipated in the discovery 

 of benzene, in the following terms : — 



"It is usually stated that benzene was discovered in 1825 by Faraday in 

 the liquid separating from condensed oil gas, but Schelenz (Z. angew. Chem.,. 

 1908, p. 2577) has shown that the compound which we now term ' benzol ' 

 or more recently ' benzene ' had been discovered in coal-tar forty years before 

 Faraday, in the year 1825, reported * On New Compounds of Carbon and 

 Hydrogen and on certain other Products obtained during the Decomposi- 

 tion of Oil by Heat.' In Macquer-Leonhardi's ' Chymisches Worterbuch,' 

 published at Leipzig in 1783, vol. i. pp. 86, 709, a passage is found which in 

 English translation runs as follows : — 



" From coal we can obtain by distillation a nearly tasteless water, a 

 brownish yellow, disagreeably balsamically smelling oil, and another em- 

 pyreumatic tougher oil which can be rectified into naphthol (that is, mountain 

 oil, in the old classic sense) like petroleum. In 1874 was published at Leipzig 

 ' Demadys Laborant,' translated into German by Samuel Hahnemann, in 

 which the distillation of coal on the large scale is described, enumerating the 

 various fractions, one of which can be at once put into bottles in which a 

 space of at least three or four fingers' breadth must be left. Even before this,^ 

 in Caspar Neumann's ' Praelectiones Chemicae,' published at Schneeberg in 



