410 Correspondence of J. Nickles. 
essence.” 
The principal fact, its molecular character, and the general consequences 
which are deduced from it, were made known to the Academ Sci 
cal analysis is applied to the study of those bodies only after they have 
ceased to exist: he explains the difficulties he has surmounted in persuad- 
interpreter. Biot closed his recapitulation of the principal discoveries 
of which the circular rotatory power of molecules had been alike the 
himself, 
On the existence of new simple bodies—The beautiful labors which 
Bunsen and Kirchhoff have recently published (see page 415) on this 
omy 
Foucault on the rays of the electrical spectrum. This physicist first pro- 
posed the use of points of gas carbon to form the voltaic are. 
studying this are in 1847-48, he discovered that the ray D of the 
electrical spectrum coincides with that of the solar spectrum, and hence 
nay produce a superposition of two spectra, by throwing on the 
voltaic are a solar image formed by a convex Jens. When metals, which 
produce the ray D only feebly, as iron or copper, are used as poles, 
remarkable intensity can be secured, by touching them with a salt of 
potash, soda, or lime. 
Foucault further adds :—* Before inferring anything from the constant 
presence of the ray D we must ascertain if its appearance does not indicate 
the same material mingled with all our conductors, Still this phenom 
* L'lnstitut, Feb’y, 1849; see also this Journal, [2], xxix, 424. 
