310 Intelligence and Miscellaneous Articles. 



ON THE RED DISPERSED LIGHT IN A SOLUTION OF CHLORO- 

 PHYLL. BY THE PRINCE OF SALM-HORSTMAR. 



From the statements of Stokes it appears as though the red di- 

 spersion was only to be seen in directions perpendicular to the inci- 

 dent ray ; this, however, applies only partially to the phsenomenon. 

 I have observed that the red light can be distinctly seen, even when 

 the test-glass containing the solution of chlorophyll is held so that 

 the flame of a lamp is placed nearly between the glass and the eye 

 of the observer. In order to avoid mistake, I put a piece of black 

 velvet into the fluid so as to prevent the hinder surface of the glass 

 from giving any reflexion ; but the red dispersion remained as before. 

 The red light consequently radiates also in the opposite direction to 

 that of incidence. 



It is remarkable, however, that this fluid should also show the red 

 light in the opposite direction ; that is to say, in the direction of the 

 incident ray, as soon as the solution is so concentrated that the 

 directly visible light becomes more obscured. 



As the so-called dispersed light promises to do much to elucidate 

 the phsenomena of hght, the smallest circumstance deserves to be 

 kept in mind. 



From the well-known fact that the red dispersion is only seen 

 with the help of a burning-glass in the centre of the solution of 

 chlorophyll, it would seem that those invisible rays of sun-light which 

 are rendered visible by the chloi-ophyll are separated in the sun-light 

 by heterogeneous spaces, just as though they passed through a lat- 

 tice, which only causes those atoms lying close to the surface to 

 become luminous, where it is permitted by the lattice, and complete 

 their course at that point. Thus in the parallel state the red di- 

 spersion is visible at the surface ; in the converging state, also, in the 

 centre. The question then arises, whether this might not be em- 

 ployed in measuring these parallel heterogeneous intervals ? — Pog- 

 gendorfF's Annalen, vol. xciv. p. 467. 



MOLECULAR CONSTITUTION OF CRYSTALS. 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, Dublin, August 4, 1855. 



IN my paper on the Molecular Constitution of Crystals, which 

 appeared in the Philosophical Magazine for August, I repre- 

 sented Sir David Brewster as having said that the cleavage of cry- 

 stals arises from the unequal cohesion of the different poles of each 

 molecule. 



Quoting his words from memory, I erroneously considered them 

 to apply to the first system of crystals of which I was then speaking ; 



