1844-54' .VARIOUS RESEARCHES. 187 



London, to draw up a report on the present state of oph 

 thalmic science in England. So deeply impressed was he 

 with Dr. Wilson's work, that he expressed his opinion of its 

 value in the following terms : " Though I have abstained 

 from making special reference to books, I cannot pass over 

 the admirable and original work on chromato-pseudopsis, 

 or colour-blindness, by Dr. George Wilson, of Edinburgh. 

 For acuteness and originality, this volume deserves the 

 highest praise." The opinion thus expressed was indorsed 

 by all present who had studied the subject. 



From 1846 onwards to 1852, a series of researches on 

 Fluorine was carried on, involving much patient investiga- 

 tion and laborious inquiry. Its presence was discovered in 

 waters, in minerals, fossil remains, plants, and animal secre- 

 tions. In the English translation of " Lehmann's Physio- 

 logical Chemistry," by Professor G. E. Day, special reference 

 is made to them. 1 With one or two exceptions, the papers 

 containing a record of those investigations were brought 

 before the Royal Society, Edinburgh, and have a place in 

 its Transactions. 2 The last notice of the subject was one 

 claiming priority, because of a communication made to the 

 French Academy in 1856, by M. J. Nickles, entitled l Pre- 

 sence du Fluor dans le Sang,' this gentleman being unaware, 

 apparently, of Dr. Wilson's announcement of the same fact 

 in 1850. 



Before the Royal Society of Edinburgh were also brought, 

 in 1848, the results of eight months' inquiry into the bleach- 

 ing powers of certain gases ; and in the following year the 

 f Early History of the Air-Pump in England.' In 1845, he 

 read also here, " On Wollaston's Argument from the Limita- 

 tion of the Atmosphere, as to the Finite Divisibility of 



1 Vol. 1. p. 425. Cav. Soc. Published 1852. 



2 See Appendix. 



