101 



most ardent advocate of the germ theory must allow that 

 there are physical and chemical phenomena attending dis- 

 ease which must not be neglected, and to these Dr. Smith 

 chiefly confined his attention, now and then only reverting 

 to the general question of the causes of disease, as to which 

 he was always prepared to change his opinions when the 

 progress of discovery required him to do so. The results of 

 his labours are contained in a series of papers, of which the 

 Royal Society's catalogue contains a list, though an incom- 

 plete one, beginning with one entitled " Some Remarks on 

 the Air and Water of Towns," published in the Chemical 

 Society's Journal, 1845-48. His results are summed up in 

 an independent work entitled "Air and Rain." Much of 

 Dr. Smith's work was necessarily of a purely qualitative 

 character, for the phenomena which he investigated are 

 concerned with almost infinitesimal quantities of matter. 

 Nevertheless, whenever it was possible, he introduced quan- 

 titative methods, as when examining the amount of carbonic 

 acid contained in the atmosphere, of which an account will 

 be found in his paper " On Minimetric A nalysis," read 

 before this Society in the session 1865-66. This paper con- 

 tains a description of a very simple and ingenious little 

 apparatus, called by him a "finger-pump," by which the 

 amount of impurity in the atmosphere, in the shape of car- 

 bonic acid or hydrochloric acid, can be rapidly and easily 

 determined. On disinfectants, to which Dr. Smith's atten- 

 tion was naturally directed, he worked much, his general 

 views on the subject being contained in a separate work 

 published in 1869, and entitled " Disinfectants and Disin- 

 fection." The practical result of his studies in this direction 

 was the invention of a very useful disinfectant which was 

 introduced by Mr. Mc.Dougall, and is still largely employed. 

 This short resume of Dr. Smith's labours on air and water in 

 their hygienic relations must suffice for the present occasion, 

 but before closino; it we must not omit to name his able 



