] 62 Intelligence and Miscellaneous Articles. 



He remarks, as an objection to the binocular construction, that the 

 observation will not be convenient, if objects of very different alti- 

 tudes are to be viewed, but still thinks that it would be worthy of 

 trial in certain cases. 



XXIV. Intelligence and Miscellaneous Articles. 



ON THE COMBINATIONS OF SILICIUM. BY I. PIERRE. 



DOUBTS are still entertained as to the formula which should be 

 assigned to silicic acid, and consequently to the chloride of sili- 

 cium. Some chemists admit that silicic acid should be represented by 

 the formula SiO 3 , and adopt the number 266*82 as the equivalent of 

 silicium ; others prefer the formula SiO 2 , taking Si = 1 77*88. Lastly, 

 some are of opinion that the rational formula of silicic acid is SiO, 

 and the equivalent of silicium 88*94. 



The first of these formulas, admitted by the majority of mineralo- 

 gists, has the imposing authority of Berzelius, Thenard, &c. The 

 formula SiO-, adopted by a certain number of German chemists and 

 mineralogists, among whom m.y be mentioned M. Gmelin, possesses 

 the advantage, according to M. Cahours, of making the volume of 

 vapour representing the equivalent of the protosilicate of ethyle of 

 M. Ebelmen enter within the ordinary conditions. Lastly, the for- 

 mula SiO seems at present to be generally admitted by the majority 

 of French chemists ; it was proposed long since by M. Dumas, when 

 he published his beautiful investigation upon the specific gravities 

 of vapours. M. Ebelmen, in his interesting memoir upon silicic 

 aethers, has adopted this latter opinion after a very learned and pro- 

 found discussion. 



As the curious facts of the aetherification of silicic acid do not 

 appear to have resolved the question completely in the eyes of a 

 certain number of chemists, I proposed in the present investigation 

 to ascertain whether it might not be possible to obtain, either by 

 some facts of substitution or by the production of some double 

 chlorides analogous to the double fluorides already known, or lastly, 

 by the production of some new aether or amidogen compounds, 

 results of such a nature as would allow chemists to base their selec- 

 tion upon more explicit and varied data. 



The difficulties encountered in the preparation of the majority of 

 these various kinds of compounds, the long and tedious manipulations 

 required by researches of this class, in which the chloride of silicium 

 is the first indispensable material, — all these circumstances combined 

 did not admit of my varying and multiplying the operations to the 

 extent I desired ; but imperfect and incomplete as they are, I think 

 they deserve to fix for a moment the attention of chemists. 



I. Compounds derived by Substitution from the Chloride of Sili- 

 cium. — The facts exposed in this first part of my investigation may 

 be resumed in the following propositions : — 



1. The chloride of silicium may be deprived, at a high tempera- 

 ture, by the action of hydrosulphuric acid, of the whole of its chlo- 

 rine, and the latter replaced by an equivalent quantity of sulphur, 



