80 REPORTS ON THE 3TATE Of SCIENCE. 



be removed from the electrode by a solution of hydrogen peroxide in 

 diluted sulphuric acid. 



Experiments on the separation of the four metals — copper, anti- 

 mony, tin, and lead — have been continued. In connection with this 

 work it has been shown that chlorides exert a retarding influence on the 

 deposition of copper. This is due to the formation of derivatives of 

 cuprous chloride during electrolysis from which copper is only deposited 

 at a high potential. The conditions for the separation of copper from 

 antimony have been fully elaborated, and mixtures of the three metals 

 —copper, antimony, and tin — corresponding to industrial alloys have 

 been successfully analysed. When lead is present in small quantity 

 this may be deposited with the tin ; the greater part of the tin may after- 

 wards be removed by making the electrode the anode in a solution con- 

 taining sodium polysulphides. The lead may then be separated from 

 the small quantity of remaining tin by means of nitric acid, and can 

 afterwards be deposited electrolytically. 1 



Dynamic Isomerism. — Report of the Committee, consisting of Professor 

 H. E. Armstrong (Chairman), Dr. T. M. Lowry (Secretary), Pro- 

 fessor Sydney Young, Dr. C. H. Desch, Dr. J. J. Dobbie, Dr. 

 M. 0. Forster, and Dr. A. Lapworth. (Drawn up by the 

 Secretary.) 



Absorption-Spectra of Camphor and its Derivatives. 



The study of a large number of derivatives of camphor 2 has shown 

 that a band is normally present at a frequency 1/3500, but penetrating 

 only to log. thickness 2 - 6 (about 400 mm. of N/1000 or 40 mm. of 

 N/100 solution). This band appears even when the two hydrogen- 

 atoms of the adjacent methylene group are displaced, provided that the 

 new radicles do not possess any large residual affinity ; but in compounds 



/CBr 2 

 such as aa'-dibromocamphor, C 8 H 14 / , and oa'-chloronitro- 



x co 



/CCl.NOj 

 camphor, C 8 H 14 <f , the general [absorption is increased by the 



substituent groups, and the band disappears. The development of the 

 band can only be attributed to the carbonyl-group, which is therefore 

 capable of giving rise to a specific or local absorption : this is only of 

 slight intensity, and of such a frequency as not to give rise to visible 

 colour, but it may be compared not unreasonably with the blue or green 

 colour produced by the analogous chromophore — N = O in compounds 

 such as /?r-nitrosobutane. 



1 Preliminary note in Proc. Chem. Hoc, 1909, £5. 228 



2 Trans. Chem. Soc, 1909, C5, 807-823, 1340-1346; 1910, 97, 899-905, 905-921. 



