148 Scientific Intelligence. 
apparatus was similar to that of Magnus, with the exception that 
a brass cylinder was cemented upon the glass vessel; instead of 
the thin glass plate a polished metallic surface, constituting the 
bottom of the brass vessel, faced the enclosed thermometer, a 
double wall surrounded the cylinder filled with cotton wool to pre- 
vent too rapid cooling. The glass cylinder was 20 em. high and 
7°5 em. in diameter-—its lower edge was ground so as to fit air-tight 
upon the plate of an air pump. The thermometer in Magnus’ 
d of 
air.” —Phil. Mag., Dec. 1877, page 401. 
11. & of the Electrie Spark in compressed gases.—CAZIN 
and Winer have been experimenting separately upon the sub- 
ject. Cazin resses his results as follows: The electric spark 
resembles an ordinary gas flame. In both sources of light there 
are, beside the peculiar vaporous particles which give line spectra, 
e admixture of the last which arises from the character of the 
electrodes and sides of the containing vessel increases with the 
pressure, so that finally the line spectrum upon the higher con- 
tinuous spectrum disappears. In the so-called aureole the mate- 
