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J. W. Langley—Chemical Affinity. 373 
sulphocyanides of iron;” the chemical action of light by 
the late J. W. Draper,” in this country, and Professor H. E. 
Roscoe™ in England, as well as Becquerel™ in France, pioneers 
who have since been followed by a host of students of scien- 
tific photography. 
In th 
e review just given noattempt has been made to do 
more than glance at the important contributions to the theory 
and methods of measuring affinity. Many names have been 
passed by and much work has been necessarily ignored owin 
to the limits of time and space which surround the writer of 
an address like this; but notwithstanding the presence of 
those limits, et my consciousness of how greatly your patience 
has been drawn upon, I will venture to add a few words on 
one other shade: of the subject, and that is The Haisting Problem. 
LIST OF AUTHORITIES QUOTED. 
1. H. Debus: Ann. Ch. Pharm., lxxxv, | 23. Thos. Andrews: Phil. Trans., 1844; 
3: also Phil. Mag., xxxii 392, fol- 
2. Barchusen: Spheig asset 1698. lowed by a series of papers on 
3. H. Debus: the same subjec 
4, Wurtz: Dice ‘Chim. article Affinité. | 24. Thos. Wood: On the heat of Chem- 
5. Idem. ical Combination. The first of the 
6. Torbern Bergman: De Attractioni- series is in Phil. 7 C4} = 268. 
bus Blectivis 1775; also in the 3d | 25. Favre and Silberm 7 Oh. 
volume of his Opuseula Torberini- Phys. [3] xxxiv, “385, saath in sue- 
eign Phy s. et Chemica, 1783. ed volumes. 
7. H. Debus: 26. J. Thomsen: Pogg. Ann., 
8. Charles Daubeliy® rae to 349, and in following volumes. 
the Atomic Theory. 2de 5.| 27. Alex. Naumann: Lehr- und Hand- 
9. ©. L. Berthollet: Bs de Sieeawe buch der Thermochemie, 1882. 
Ses 180 28. H, St. Claire Deville: Compt. rend., 
10. Sir Davy: Paik Trans., 1807; xlv, 857; also in the cae de 
Pee 18 Chimie of the Paris Chemical So- 
11. Wurtz Dict: loc. cit. ciety, on Dissociation, 1864, and 
12. Amadeo Avog ado: Journal de> on Affinity, 1867. 
a esi, p. 58. 29. Wurtz Dict.: loc. cit. 
13. B.C. die: Quar. Jour. Chem. 30. yer niece and Tribe: A Law in 
ag nh 194. Chemical Dynamics ; Sos Roy. 
14. D. Mendelejeff: Zeitschrift fiir Soe., is, 498, 
Chemie, 1869, 495; and Annalen 31. R. B. Warder: Suggestions for com- 
er Chemie, 8 suppl, puting the Lak oF ere agee eon 
15. Lothar Meyer: Ann. der Chem., 7 actions; Proce. Rte 
suppl., 356. 156. 
16. J. Newlands: Chem. News, x, 59- 32. J. H. Gladstone: Chemical Affinity 
xisting among Substances in 
17. Watt’ Dict. : = i, p. 865. Solution; Phil. Trans., Mar., 1864. 
18. A Will : A Theory of 33. J. W. Draper: Chemical action of 
“Eiherfeation aan Jour. Chem. Light; ea Frank. _ xix, 
0c., iv, 1 469. a ; also many others on 
19, J. B. Richter: Anfan gsgrunde der the same subject in Phil. Mag., 
aefehiseeeee Breslau, 1792. from 1842 to 1857. 
20. Willia iggins: A Comparative 34. H. E. Ros easurement of the 
e Phiogistic and Anti-| Chemical Action of Light; Proc. 
phlogistic Theories, 1789. | oy. Soc., 1857, 326; also in con- 
21. Wurtz Dict.: Affinité, p. 72. | junction with Bunsen till 186 
22. F. Guthrie: Phil. Mag. [4] xlix, ls 36. Edm.B ical rays which 
of several pape accompany Light; Compt. rend., 
E e 
by him on Cryohydrates. 
[To be concluded.] 
