84 Intelligence and Miscellaneous Articles. 



meter, having a steel surface. These two cylinders were connected 

 end to end by a thin copper wire, the interval bridged over by this 

 wire being about -J- inch. The other ends of the cylinders were 

 similarly connected to the polar terminals of a Bunsen cell half 

 charged (8 water -sulphuric acid ; commercial nitric acid; amalga- 

 mated zinc cylinder 6 inches by 3 inches). These terminals were 

 made from a rope of four No. 16 copper wires twisted together ; each 

 was about 18 inches long. After waiting two or three minutes, the 

 steel-covered cylinder was found to be much hotter than the copper 

 covered. This was quite sensible to the fingers ; but the most satis- 

 factory way to obtain conviction was to approach the middle part of 

 each with the outer dry part of the lips. It was possible to keep 

 the copper- covered one pressed to the lips for a second or two, but 

 not so with the steel-covered one. The heat was so considerable in 

 it that it was not possible to touch it for an instant without sharp 

 pain. These temperatures were persistent. 



Taking copper as having -J-th the resistance of steel, and the rise 

 of temperature to be in the inverse ratio of the 4th power of the dia- 

 meter of the cylinders or conducting- wires (De la Rive's ' Electricity,' 

 vol. ii. p. 224), the temperature of these two cylinders ought to 

 be nearly the same if the force is conducted by the whole thickness 

 instead of by the surface alone ; whereas, if by the surface alone, 

 the rise of temperature in the steel- covered one ought to be three or 

 four times that in the copper-covered one. J. J. Waterston. 



ON THE COLORATION OF GLASS BY SELENIUM. BY M. J. PELOUZE. 



I determined, some months ago, that the yellow colour acquired 

 by glass under the influence of carbon, phosphorus, boron, silicium, 

 hydrogen, and aluminium was due to the constant presence of a sul- 

 phate in the glass of commerce, and that glass remains perfectly 

 colourless under the influence of these various metalloids when it 

 has been prepared with fluxes completely free from sulphur. Hence 

 the coloration in question must be owing to the sulphur exclusively ; 

 and I have proved this to be the case by directly colouring pure or 

 impure glass with sulphur or a sulphuret. 



It then became a curious question to determine whether selenium, 

 which has every possible habit and analogy with sulphur, would also 

 directly colour glass, and what colour it would impart to it. 



I had preserved a specimen of perfectly pure selenium, which the 

 illustrious author of its discovery gave me thirty years ago. I mixed 

 it with the ordinary glass composition prepared with the carbonate, 

 and obtained a perfectly transparent matter, of a beautiful orange- 

 colour inclining to red, and resembling certain varieties of topaz, 

 essonite garnet, and hyacinth zircon (fifth orange-red y 3 ^, ninth 

 shade, M. Chevreul). 



I varied the proportions of selenium from 1 to 3 per cent., and 

 always obtained a colour of the same shade and intensity. Some pur- 

 chased selenium gave the same result. 



This experiment proves that the long-known analogies between 

 sulphur and selenium extend to their action upon alkaline and earthy 

 silicates, and that these two metalloids directly colour glass. — Comptes 

 Rendus, October 16, 1865. 



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