Manchester Memoirs, Vol. Iv. (1910), No. 14. 3 



fested in his last bequest to me of what he had most prized 

 in Hfe." This was the bequest of all his chemical and 

 philosophical instruments and apparatus. Other proofs 

 of this friendship can easily be found. There is the 

 dedication of Dalton's " New System of Chemical 

 Philosophy " (vol. i., Part 2) to William Henry (along 

 with Humphrey Davy), and of Henry's " Elements of 

 Experimental Chemistry" (6th Ed., 1810) to Dalton. 

 Again, Dalton took an opportunity in 1827 of acknow- 

 ledging his friendship with William Henry. " It affords 

 me great pleasure to acknowledge the continued and 

 friendly intercourse with Dr. Henry, whose discussions on 

 scientific subjects are always instructive, and whose stores 

 are always open when the promotion of science is the 

 object."^ 



There is no room for doubt that the reports of these 

 conversations with Dalton are perfectly authentic. W. C. 

 Henry states that he noted down Dalton's expressions 

 " immediately after each lesson," and the passage which 

 has been quoted, regarding the influence of Richter, is 

 copied, he says, " verbatim from my own journal when his 

 pupil."* Nevertheless, Henry knew there was something 

 wrong. The date of his conversation with Dalton was 

 February 5, 1824, and he says, "on reviewing in con- 

 versation, after the lapse of twenty years, the labours of 

 the past, Dalton himself may have failed in recalling 

 the antecedents of his great discovery in the exact order 

 of sequence"^ 



Again, the Richter story is strongly challenged by 

 Thomas Thomson. "When I visited him in 1804 at 

 Manchester both Mr. Dalton and myself were ignorant of 



" "New System of Chemical Philosoph}-,'' vol. 2, p. 8, 1827. 

 * Ibid., p. 84. 

 ° Ibid., p. 86. 



