SW Scientiftc Intelligence. 



for containing the pulverized glass, which was to be subjected to the final 

 melting in a furnace of peculiar construction, which the author terms the 

 finishing furnace. After numerous trials of substances for constructing 

 the chamber in which the fusion of the glass contained in the tray was to 

 be conducted, recourse was had to the materials from which the Cornish 

 crucibles are manufactured, and which were obtained through the kind- 

 ness of the president, and were expressly manufactured for the purpose by 

 Mr Mitchell of Cornwall. In order to prevent the reduction of any por- 

 tion of the lead entering into the composition of the glass, a current of 

 fresh air was introduced by a tube, and made to pass along the surface of 

 the fused glass. A very minute and circumstantial account is given of all 

 the manipulations necessary for conducting these processes in all their 

 stages ; in some of which, however, the best methods of proceeding yet 

 remained to be ascertained — variations having been made up to the very 

 last experiment ; and it is only by still more extensive experience that the 

 author expects the proper arrangements will ultimately be settled. Direc- 

 tions are given as to the occasional inspection of the glass during the pro- 

 cess, the mode of stirring by a rake of platina, and the plan devised by the 

 author of accelerating the disengagement and escape of bubbles, by throw- 

 ing into the melted materials a quantity of pulverized platina mixed with 

 fragments of the same kind of glass. The glass which has been obtained 

 by the mixture of the materials above-mentioned, constituting silicated 

 borate of lead, has a specific gravity of 5.44, and high refractive and dis- 

 persive powers, and, perhaps, also very considerable reflecting power.* It 

 is softer than ordinary glass, but less liable to be tarnished by sulphureous 

 vapours, as they usually exist in the atmosphere ; and also less acted upon 

 by moisture than glass into which potash enters as an ingredient ; it is 

 likewise a much more perfect electric than common glass. — Lit. Gazette. 



2. Effect of light on Liquids. By M, Dutrochet. — On the 18th Ja- 

 nuary 1830, M. Dutrochet addressed a letter to the Institute, the object of 

 which was to establish that light is an occasional cause of motion in liquids, 

 and that water in the state of liquidity possesses two very different molecular 

 states, v/hich appear to be analogous^ the one to a regular aggregation, and 

 the other to a confused aggregation of solid molecules. 



On the 25th January, the Institute received from M. Dutrochet a second 

 communication relative to the influence of light on the motion of liquids. 

 He had established that a difference of temperature was the efficient cause 

 of the circulating motion in liquids, ^g© of a degree of difference being 

 sufficient with the aid of light. New experiments have proved that in the 

 absence of this agent ttie circulating motion stops. When the windows 

 are shut, so as to leave only enough of light to distinguish the circulating 

 motion when it exists, this motion is immediately suspended. When the 

 windows are again opened the motion recommences. When it is again 

 completely suspended by the absence of light, if v/e tap upon the table on 

 which the tube rests, this slight movement instantly re-establii-hes the cir- 



• The less reflecting power the better ; but this depends entirely on the refractive 

 power— Ed. 



