It will be remembered that M. Armand Gautier, as the result of very elaborate investigations, was led to the conclusion that air, even from the Atlantic, contains by volume nearly two parts in 10,000 of free hydrogen. The presence of so much hydrogen, nearly two-thirds of the carbonic acid which plays such an important part, is of interest in connexion with theories pointing to the escape of light constituents from the planetary atmospheres. Besides the free hydrogen, M. Gautier found in the air of woods and towns considerable quantities of hydrocarbons yielding CO2 when led over hot copper oxide.

Spectrosopio Evidence

In the Philosophical Magazine for Jan. 1901, I described some observations upon the spectrum of sparks taken in dried air at atmospheric pressure, which seemed “to leave a minimum of room for the hydrogen found by M. Gautier.” Subsequently (April 1901), these experiments were repeated with confirmatory results. The spectra, taken from platinum points, of pure country air and the same to which of hydrogen had been added were certainly and easily distinguished by the visibility of the C-line. An improvement was afterwards effected by the substitution of aluminium points for platinum. A strong preliminary heating reduced the C-line with a stream of pure dried air to the least yet seen, only just continuously visible, and contrasting strongly with the result of substituting the air to which the two parts in 10,000 of hydrogen had been added.