370 Proceedings of the 



sulphates, rotten wood or fish, &c. There are numerous other cases 

 in which phosphorescence may be explained by the recomposition of 

 the two electricities disengaged in consequence of a derangement in 

 the molecules of bodies. On cleaving a crystal light is frequently 

 observed, which is evidently electric. But may we not also attri- 

 bute the phosphorescence produced by heat to a partial cleavage, 

 or a displacement of the superposed plates ? If certain bodies, 

 after having been highly heated, lose the property of becoming 

 phosphorescent, is it not because the heat has produced in the rela- 

 tive situation of their molecules a derangement which renders those 

 regular displacements impossible ? And is not the luminous ap- 

 pearance produced by percussion, and even that produced by 

 grinding, when no free electricity is disengaged, to be attributed 

 to another change in the position of the molecules, and consequently 

 to an electric decomposition and recomposition ? By a similar appli- 

 cation of the same principle, M. Becquerel accounts for the phos- 

 phorescence observed in some bases, such as zircon, which, when it 

 is produced, deprives those bases of their faculty of combining with 

 the acids. Finally, M. Becquerel considers that the phosphorescence 

 produced by electric discharges, which is observed in bodies which 

 are bad conductors, depends on a species of cleavage which gives 

 rise to a decomposition and recomposition of electricity. This action 

 is only successive on account of the bad conductibility of the bodies ; 

 and during the whole time that a portion of the two electricities 

 which have become free remains engaged between the molecules of 

 a body, that body has a luminous appearance. 



Bromide of Silicium: New Chemical Compound. On the 

 26th of September, M. Serullas read a note on a new compound of 

 bromine and silicium, which he calls bromide of silicium. This com- 

 pound is obtained by mixing lamp-black, pulverized sugar, and a 

 sufficient quantity of oil to form a homogeneous paste, with silica, 

 hydrated and desiccated to a certain point. This paste must be cal- 

 cined in a covered crucible. The quantity of carbon contained in the 

 different substances employed should be above half the weight of the 

 silica. The carbonaceous and spongy residue of the calcination is 

 introduced in small fragments into a porcelain tube, at one of the 

 extremities of which is fixed a small retort containing the bromine, 

 and at the other a tube, which terminates in a globe or balloon, 

 surrounded with ice, and having affixed to it a long tube, terminated 

 by a narrow opening. The porcelain tube being made incandescent, 

 the bromine is volatilised by slow degrees by means of heat ; the 

 bromide of silicium is produced and condensed in a liquid form in the 

 tube and receiver. When the operation is terminated, the bromide 

 should be re-distilled, in the manner pointed out by M. Oerstadt 

 for the chloride of the same base, after having shaken it, in the 

 same retort in which it is to be distilled, with mercury, in order to 

 get rid of the excess of bromine ; this produces a magma of greater 



