AMERICAN 
JOURNAL OF SCIENCE AND ARTS, 
[THIRD SERIES] 
Arr. XXIII. — Researches in Actino- Chemistry. Memoir First. 
On the Distribution of Heat in the Spectrum ; by JoHN WIL- 
U5: dit 
Science and of Medicine in the University of New York. 
the maximum of intensity in both occurs at the same point, 
at Is, in the yellow space. This view was abandoned on the 
Publication of the well known experiments of Sir W. Herschel, 
who showed that in certain cases the maximum is below the red. 
Subsequently Melloni having discovered the singular heat- 
dsparency of rock-salt, proved that when a prism of that 
Substance is used the maximum in question is as far below the 
ed as the red is below the yellow, but that if the light has 
Passed through flint-glass the maximum approaches the red, if 
through crown-glass it passes into the red, if through water or 
alcohol it enters the yellow. 
€ case of the sun’s spectrum the distribution of heat was 
More closely examined by Prof. Miiller, whose results in a gen- 
eral manner confirmed the views then held, that the invisibie 
tadiation below the red greatly exceeds that in the visible spec- 
; and still more recently Dr. Tyndall, examining the spec- 
ttum of the electric light through rock-salt, showed that th 
“utve indicating the distribution “in the region of the dar 
“ays beneath the red, shoots suddenly upward in a steep and 
Massive peak, a kind of Matterhorn of heat, which quite 
Am. Jour, Sce1.—Tairp — Vou. IV, No. 21,—SepremBer, 1872, ; 
