Intelligence and Miscellaneous Articles. 571 



tromotive force, originally = 139, fell to 113; but a rest of 40 

 minutes raised it to 129, and at the end of two hour3 it was at 138. 



We have taken great care to reduce as much as possible the in- 

 ternal resistance of the element: the zinc surrounds the porous 

 vessel at a very little distance ; and we avoid touching it by inter- 

 posing two rings of pack-thread. 



The odour of the chloride of lime is not perceptible, because the 

 vessel is closed with a cork covered with pitch, which prevents the 

 liquid from being spilled in conveyance, and the salt from evapora- 

 ting. One perforation only is made in the cork, for pouring the 

 water into the pile at the moment of setting it in operation. — 

 Comptes Benches, Oct. 27, 1879, t. Ixxxix. pp. 703-705. 



ON THE ABNORMAL SPECTRUM OF LIGHT. 

 BY M. DE KLERCKER, OF STOCKHOLM. 



The anomaly produced in the spectral position of various rays of 

 light when dispersion is occasioned by solutions of certain colouring 

 matters has for several years past deservedly attracted attention. 



The rays, of different sorts, whose index of refraction increases 

 in ordinary cases in proportion as the length of the luminous waves 

 diminishes from one end of the spectrum to the other, are here 

 thrown out of their normal positions ; moreover this change of posi- 

 tion may be carried to such a degree that the usually most refran- 

 gible rays, the blue and the violet, appear the least refrangible of 

 all, as is best proved when the light is dispersed by means of a solu- 

 tion of fuchsine (aniline red). 



There is, however, nothing in this phenomenon which would dis- 

 close in a decisive manner the presence of an irregularity in the 

 dispersion which would be called forth by the molecules of fuchsine 

 acting alone. But if we must seek elsewhere the origin of the 

 anomaly, we shall be led to admit that the refraction of light by 

 the fuchsine solution takes place for certain rays on quite another 

 scale than for the rest ; and as this property of the solution is a 

 consequence of the presence of the molecules of the colouring ma- 

 terial, we may thence conclude that these must possess the hitherto 

 unknown property of retarding only certain luminous rays while 

 they permit the others to pass freely. 



This explanation appears to me to have been completely verified 

 by the spectral analyses to which I have devoted myself in the course 

 of the past summer, the first results of which I communicate today. 



Two hollow prisms of plate glass, both having the same refracting 

 angle of 25°, were placed on the platform of a spectroscope, one 

 behind the other, and the refracting angles directed oppositely. 

 The two prisuis having been filled with alcohol, no deviation was 

 impressed upon the image of the slit of the spectroscope, on account 

 of the two refractions being equal and of contrary signs. 



I then proceeded by degrees, adding successively to the alcohol 

 of one of the prisms small quantities of crystallized fuchsine, leav- 

 ing the alcohol of the second prism pure. The following were the 

 observed effects : — 



The primitive image became divided into two parts, which sepa- 



