4«0# iHtdligenee and 'MisMllimeom Articles. 



'8ol*r .TiiBlqait'niiciJib production Jcri'jjwAteHAi^tousijgusuiTtf'. 

 slamie bfiri iloidv/'io \i'y'BT"M.. EBELMlillfriHiB ,sJifiirp to vJemv aifi-K 



When either of the two silicic asthers which I have'^d^fir^^ff^' 

 scribed* is exposed to the continued action of a moist atmosphere, 

 the liquid finally solidifies to a transparent mass. This prodiK^r 

 very delicate and fragile in the first days after its solidification, cod- 

 tracts more and more under the influence of the moist air still rt^-' 

 maining diaphanous. Two or three months are requisite in ope- 

 rating on 5 or 6 grms. of aether, for the substance to cease to lose iij 

 weight and for its molecular movement to terminate. The substance 

 prepared as above is hard, faintly scratches glass, and possesses 

 great cohesion ; its lustre, its fracture and transparency are per- 

 fectly comparable to the most beautiful rock crystal. Its density f^ 

 1-77. It is a hydrate, which contains twice as much oxygen in the 

 silica as in the water, the formula ^jf'^^fc^ is consequently (SiO)'^ 



HO. ■ v\C?.0Vsi\*\ :• 



It is essential, in order that the product may not become fissured 

 during the contraction it experiences before attaining the definite 

 formula (SiO)'- HO, pot to allow the moist air to enter except by ai^ 

 aperture of very small diameter. During the whole of the experi- 

 ment the flask containing the silicic aether exhales an alcoholic 

 odour, which persists a long time after the solidification, proving 

 that only a portion of the organic matter had separated from the 

 silica when the solidification took place. The contraction proceedp^ 

 the more slowly the less easily the moist air is renewed in the appa-^ 

 ratus, and this slowness appears indispensable to the success of the| 

 operation. 



From the properties of the hydrate of silica, we may be allowed 

 to hope that it may be turned to advantage in the construction of 

 optical instruments. It is my intention to make some experimentgi^ 

 in this direction. — Comptes Jtendus, Aug. 25, 1845. m 



-oiq bnj? ' ; yd ii 



-9b0X#fiiTi^^.^PyiEl9;AL PRODUCTION OF^HpROPH^^^ 



-m£ JbxIJ am baftaiisa elfBIS^^' ^^^LSf^^gT^^g \q^ ; anirienua ^im. 



■"TBy slight jr-mbcBfying the process for the prepaf atjon :<)f ;by<Jr^te 

 of silica, described in the preceding paper, there is obtained, in- 

 stead of a diaphanous product, an opake substance, which become^ 

 entirely trajisparent when placed in water, in a word, true liydron 

 phane. It suffices for this purpose that the silicic aether employed 

 retain a little chloride of silicium, which happens when an excess 

 of alcohol has not been employed in the preparation of the sethert 

 On exposing this aether, still somewhat acid, to the action of moist 

 air, there is obtained a solid mass, which is at first transparent, 

 but ends by becoming opake after some weeks' exposure to the aii?| 

 The translucidity of this substance is so much the less the greater 

 the proportion of the chloride of silicium in the ajther. Some of the 

 fragments have the semi-trunspai-tney of opal. They all become 

 entitely .transpareiil ill. water. . ., ^..„i. .j 



oldBjIijsrnai ei ^JS^C^^eg Pliil. Ma;;, vol. xxv. i^/sfe?^*^^ ^^-^^ sbbo riofia 



