120 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



angle. The metals of high atomic weight volatilize most 

 readily. 



Barat proposes to use, for the Franklin portrait experi- 

 ment, in place of a gold leaf, a gilded plate of glass, having 

 two strips of tin-foil across the ends and the portrait outline, 

 paper and press as usual. One spark is sufficient; a second 

 uniformly breaks the apparatus. 



Gripon has published two interesting experiments in stat- 

 ic electricity. In the first, two equal strips of copper are 

 placed at the top of a metallic stem, the lower one fixed, the 

 other moving on a pivot. If the apparatus be placed in the 

 neighborhood of an electric machine, or even of a charged 

 sphere, the two strips arrange themselves perpendicularly to 

 one another. If the upper strip be replaced by a magnetic 

 needle, a deflection more or less decided is also observed. 

 In the second, a capsule completely full of oil of turpentine 

 is placed beneath a permanently electrified sphere. The liq- 

 uid is attracted, and a column of it rises to the ball, in which 

 very complex movements may be observed, the whole recall- 

 ing closely a water-spout. 



Berthelot having proved that even under the ordinary 

 electric tension of the atmosphere a silent discharge may be 

 caused in a tube containing nitrogen, by means of which 

 this gas may be absorbed by organic bodies to form new 

 compounds, proposes this result as one which must necessa- 

 rily go on in nature. Hence he insists upon the necessity 

 of studying consecutively and methodically the electric con- 

 dition of the atmosphere, since upon its tension this absorp- 

 tion of nitrogen depends. 



Maxwell has communicated to the Physical Section of the 

 British Association a paper on the protection of buildings 

 from injury by lightning. Premising that the precautions 

 ordinarilv taken in the construction of lisjh tiling-rods are cal- 

 dilated rather for the benefit of the surrounding country and 

 for the relief of clouds laboring under an accumulation of 

 electricity than for the protection of the building on which 

 they are erected, he goes on to advocate the protecting of a 

 powder-mill, for instance, by sheathing its roof, walls, and 

 ground-floor with thick sheet copper, since, under these cir- 

 cumstances, no electrical effect could possibly occur within 

 it by reason of any thunder-storm outside. Ordinarily, how- 



