Intelligence and Miscellaneous Articles. 333 



Position of the cold bands produced by iodine dissolved in chloride 

 of carbon, sulphide of carbon, or chloroform. 



Chloride. Chloroform. Sulphide. 



o / o / o / 



[1 28 1 30 — 



Position of the lines \ 1 34 — 1 35 



[l 55 1 57 1 56 



We do not pretend that these are the only lines these solutions 

 of iodine can produce ; indeed we hope to complete our Table in a 

 subsequent communication. But the numbers it contains show 

 already the conservation of the action of iodine in its three solutions. 



We will add in conclusion, that in all our experiments we always 

 compelled ourselves to study the action of the vessel full of the sol- 

 vent alone upon the region of the spectrum where the iodine-solu- 

 tion determined the production of a line, so as to satisfy ourselves 

 that the action of the solvent and of the whole refracting system had 

 no action in the production of the phenomenon, or at least very little 

 in proportion to that of the active substance properly so called. — 

 Comptes Rendus cle Y Academic des Sciences, September 6, 1875, pol. 

 lxxxi. pp. 423-425. 



EXPERIMENTS ON THE PLASTICITY OF ICE. 

 BY PROF. DR. FR. PFAFF. 



The phenomenon of glacier-motion has induced most of the 

 natural philosophers who occupied themselves with it to institute 

 experiments on the behaviour of snow and ice in relation to pressure. 

 The brothers Schlagintweit and Tyndall were the first who made 

 experiments of the kind with respect to the behaviour of glaciers. 

 Subsequently Helmholtz described a series of beautiful experiments, 

 from which it resulted that, by strong pressure, snow could be con- 

 verted into ice, ice broken small could be converted again into a 

 homogeneous cylinder, and such a cylinder be pressed through 

 apertures of smaller diameter, and more of the like kind. It was 

 thereby proved that ice under strong pressure can be brought into 

 any form desired, and consequently presents the same plasticity on 

 the small scale as is exhibited on the large scale by the mighty ice- 

 streams of glaciers, which also adapt themselves to the narrowings 

 and widenings of the valleys along which they flow. The pheno- 

 menon discovered by Earaday in 1850, which was afterwards so 

 frequently discussed under the name of regelation, gave the key for 

 the explanation of this. So far as I know, none of those named 

 above, nor any other physicist has sought to determine the pressure 

 under which ice changes its form ; all have worked with great 

 pressure, which is in fact necessary in order quickly to obtain 

 visible results. Only Moseley * instituted several series of experi- 

 ments for the purpose of ascertaining at what pressure or pull ice 

 is rent asunder, is crushed, and its plasticity becomes perceptible — ■ 



Phil. Mag. S. 4. vol. xxxix. p. 1. 



