Chemistry and Physics. 147 
Cook’s objection that the preponderance of hydrogen and CO in 
meteorites is inconsistent with the idea that the meteoric gases 
have been absorbed in space, Siemens ‘iii that it is sufficient 
to know that the meteorites contain all the constituents of our 
atmosphere except hydrogen: and the latter occurs in our atmo- 
sphere combined with o ygen; ereas in space and in the 
solar photosphere, we have evidence of its separate existence, or 
m combination with carbon. J) ok’s criticism upon la 
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electric potential supposed to exist between the sun and the 
earth except by the adoption of Sir William Siemens’ ab priate 
—Phil. Mag., July, 1883, pp. 62-66. 
5. Metal Microphones in Vacuo.—The action of the micro- 
phone is doubtless a complicated one, and cpp ments whic! 
interest. Mr. J. Munro ha. te a mic rophone from two 
he Iron gratings or pieces of gauze which hang loosely against 
each other in a tube which has been exhausted as completely 
as possible. The contacts between the wire gratings could be 
modified by brin ing a magnet to the exterior of the tube and 
r 
so could not have been supposed from certain experiments 
Edlund on the polarization of electrodes in vacuum a il. 
Mag, July, 1883, pp. 23-25. 4 Mes 
6. Carbonic acid in air helps in condensing watery eR we 
Professor Scaccar, in view of the production of clouds of vapor 
ree oe the combustion.— Nature of has 24, 
