Chemstry and Physics. 323 
2. On the light which appears on Rotoreen Electrodes which are 
placed in hydrogen gas at different pressure . Louse describes 
the spectroscopic appearance of glowing sneha electrodes sara 
in an atmosphere of hydrogen “and of magnesium vapor. 
apparatus consisted merely “of suitable vacuum tubes jiddletion 
coils and a spectroscope. It a appears from etre observations that 
the Aepeadenss of the formation of metallic vapor upon the den- 
sity of the gas surrounding the metallic electrodes can be studied 
quantitatively by the use of a constant current of electricity. It 
also perceived that with increasing rarefaction of the hydrogen 
the light intensity of the metallic vapor increases in the more 
eon pl portion of the speectrum.—Ann. der ie se 
Chemie Lh 
. The 
: 
0. 
% line in the Solar spectrum.—Professor C. A. Vou UNG, 
be means of a Rutherfurd grating of 17280 lines to the inch, and 
by means of the spectrum of the third order, has discovered that 
unit of Angstrém’s scale; also, that the line 5207-4 is double. 
These observations possess gr eat interest, because it is claimed by 
Lockyer that these oe are basic—d, belonging to Fe and Mg, 
b, to Fe and Ni, 5207-4 Cr and Fe.— Observ tory, 1880, . 271- 
272 « Beiblitter Jes ie Physik und Ohain ty 1881, No. 
Ss 
4. Action of an intermittent beam of radiant heat upon Gase 
ous matter.—Protessor TYNDALL in a paper read sete the Royal 
ociety, Jan. 3, 1881, reviews the criticisms of various experi- 
menters upon his investigations in radiant heat, mid believes their 
interpretations to be due to a failure on the part of the critics to 
recognize the strength of his position as a whole. He has taken 
up the subject anew mei peg og pee to submit the results in due 
i erimente 
neete with a dyna si binollas Gackuak by a gas seni e. A glass 
lens was used to sinioiek ate the rays, and afterwards two lenses: 
A circle of sheet zinc provi ided at first with radial slits and after- 
wards with teeth and interspaces was caused to rotate rapidly 
across the beam near the focus. A flask containing the gas or 
through the vapor. These are the most highly absorbent vapors 
