JOSEPH BLACK: HIS LIFE AND WORK 71 



chemico-physical literature dealt with the boiling of ether 

 on the reduction of pressure, and its growing cold during 

 the process. The reason of this behaviour, however, was 

 later discovered by Black, for Cullen confined himself to 

 recording the observation. It was not long before Black 

 rendered help to Cullen as his assistant ; and Black's name 

 was frequently quoted by Cullen in his lectures as an 

 authority for certain facts. 



Black's methodical habits led him to keep a sort of 

 commonplace book, in which not merely the results of 

 his experimental work was entered, but also notes on 

 medicine, jurisprudence, or matters of taste; and he 

 practised 'double entry/ for he also kept separate journals 

 in which these notes were distributed according to their 

 subjects. From these notebooks the dates of his most 

 important discoveries can be traced. 



Chemistry, in these days, was handmaid to medicine ; 

 the influence of the iatro-chemists, founded by Paracelsus, 

 still held its sway, although certain bold investigators 

 among them Boyle, Mayow, and Hales a century before, 

 had shaken themselves free from its thraldom. And the 

 lectureship on chemistry in Glasgow was regarded as a 

 step to a more remunerative position, and was held, along 

 with the Crown professorship of medicine, by Cullen from 

 1751 to 1756. It was probably owing to Cullen's advice 

 that Black went to Edinburgh in 1750 or 1751 to finish 

 his medical studies ; perhaps another reason may be found 

 in his having had a cousin in the University, Mr. James 

 Russel, as Professor of Natural Philosophy, with whom he 

 lived. There he took the degree of doctor of medicine in 

 1754. It is true that he might have graduated in Glasgow 

 three years earlier ; but no doubt his thoroughness made 

 him wish to offer a thesis worthy of praise, and it was 

 this thesis which established his reputation. More of 

 this hereafter. 



