66 Dr. Walter Flight— On Meteorites. 



an hour. IV. Low red heat maintained about half an hour. V. Full 

 red heat. The total amount of gas evolved was about two and a 

 half times the volume of the material operated upon, and twenty 

 times that of the iron. The following are the relative proportions 

 of the gases obtained at different temperatures : — 



I. II. III. IV. V. 



At 100'. At 250°. Y^\ ^*i°^, ^\^, 



red heat. red neat. red heat. 



Carbonic acid 95-46 ... 92-32 ... 42-27 ... 35-82 ... 5-56 



Carbonic oxide 0-00?... 1-83 ... 5-11 ... 0-49 ... 0-00 



Hydrogen 4-54 ... 5-86 ... 48-06 ... 58-51 ... 87-53 



Nitrogen (calculated) ... 0-00 ... 0-00 ... 4-56 ... 5-18 ... 6-91 



100-00 100-00 100-00 100-00 100-00 



As regards the gas they occlude, iron and stony meteorites show a 

 marked distinction. While the gases of the Lenarto iron contained 

 85-68 per cent, of hydrogen, those obtained from cosmical masses of 

 the stony kind, if the Iowa meteorite may be regarded as a type, are 

 characterized by the pTCsence of carbonic acid, which constitutes 

 nine-tenths of the gas evolved at a temperature of boiling water, and 

 about one-half of that given off at a low red heat. 



The spectrum of the gas of the Iowa meteorite, when the pressure 

 of the pump was high, gave very brilliant carbon bands, the hydrogen 

 lines being weak and comparatively inconspicuous, although at a 

 very low pressure they became relatively stronger. The brightest 

 carbon bands were the three in the green and blue, the red one being 

 much feebler. These are precisely the ones most conspicuous in the 

 spectra of some of the comets ; and this fact is a remarkable confirm- 

 ation of the received theory as to the meteoric character of those bodies. 



This, moreover, is a very significant fact in showing that it is 

 quite unnecessary to assume the existence of volatile hydrocarbons 

 to explain cometary spectra, as some writers have done, and that the 

 presence of the two oxides of carbon in such quantity is quite 

 sufficient to account for all that has been observed when we consider 

 the circumstance that the tension of the gases of the cometar}'^ ap- 

 pendage must be extremely small. Were a large comet to approach 

 near enough to the sun to have its nucleus intensely heated, it is 

 highly probable that, over and above the bands already observed, the 

 hydrogen lines would be found in its spectrum. 



Wright expresses regret that such a comet as Donati's should have 

 departed into space just early enough to escape observation with the 

 spectroscope. While the most probable cause of the emission of 

 light under these conditions is electricity, another may be found in 

 the property of gaseous bodies of emitting light of the same character 

 as that which they absorb. It is not altogether improbable, Wright 

 suggests, that the solar radiations absorbed by the gaseous matter, 

 although for the most part converted into heat, would also in part 

 be emitted again as light, and that in the case of volumes of gas 

 tilling many cubic inches, the intensity might be sufficient to give 

 a distinct spectrum of broad bands or lines, even though, on the 

 scale of any possible experiment, no trace of such action can be 



