Intelligence and Miscellaneous Articles, 241 



In 150 minutes 5*40 cub. centims. 



In 120 minutes 2'58 „ 



In 4 hours 30 minutes 7*98 » 



The metal has given 2G6 times its volume of gas. The first 

 portion collected appeared to contain of hydrogen 35 per cent., 

 of carbonic oxide 50'3, of carbonic acid 7*7, and of nitrogen 7 

 per cent. The latter portion collected gave more carbonic oxide 

 (58 percent.) with less hydrogen (21 per cent.), no carbonic acid, 

 the remainder nitrogen. The predominance of carbonic oxide in 

 its occluded gases appears to attest the telluric origin of iron. 



Hydrogen has been recognized in the spectrum-analysis of the 

 light of the fixed stars, by Messrs. Huggins and Miller. The same 

 gas constitutes, according to the wide researches of Father Secchi, 

 the principal element of a nnmerous class of stars, of which a. 

 Lyrse is the type. The iron of Lenarto has no doubt come from 

 such an atmosphere, in which hydrogen greatly prevailed. This 

 meteorite may be looked upon as holding imprisoned within it, and 

 bearing to us, hydrogen of the stars. 



It has been found difficult, on trial, to impregnate malleable 

 iron with more than an equal volume of hydrogen, under the pres- 

 sure of our atmosphere. Now the meteoric iron gave up about 

 three times that amount, without being fully exhausted. The 

 inference is that the meteorite has been extruded from a dense 

 atmosphere of hydrogen gas, for which we must look beyond the 

 light cometary matter floating about within the limits of the solar 

 system. 



XXXil. Intelligence and Miscellaneous Articles. 



ON A PHOTOMETER FOR MEASURING THE TRANSPARENCE OF THE 

 AIR. BY M. A. DE LA RIVE. 



ALL inhabitants of valleys know that one of the most certain fore- 

 . casts of rain is the clearness, accompanied with a bluish colour, 

 with which distant mountains are seen. This indicates the presence 

 of great moisture in the air ; but it may be asked why this moisture 

 should facilitate the transmission of light, while it is well known to 

 stop that of radiant heat, as is proved by Tyndall's beautiful ex- 

 periments. 



This phenomenon was already mentioned by De Saussure, in his 

 Essai sur VHygrometrie. "When," he says, "the inhabitants of moun- 

 tains see the air perfectly transparent, distant objects very distinctly, 

 and the heavens of an extremely dark blue, they regard rain as very 

 probable, though there appears no other sign. In fact/' adds Saus- 

 sure, " I have often observed that when for several days the weather 

 is decidedly fine the air is not perfectly transparent ; a bluish vapour 

 is seen which does not arise from aqueous vapour (for it does not 

 affect the hygrometer), but the nature of which is unknown to us." 



This influence of moisture on the transparence of the air is also 

 perceived on the surface of the sea on bright days. Thus in fine 

 weather the chalk cliff's of Dover are seen from the French coast, a 



