1886.] 



on Becent Researches on Meteorites » 



545 



For this purpose the powdered Dhiirmsala meteorite, from which 

 the gases had been removed, vvas left in moist air under a bell-glass, 

 for different periods of time as tabulated below, the gases being drawn 

 off at a low red heat after each period : — 



After 24 hours . . 

 After 6 days more 

 After 8 days more 



Occluded 

 Gas in vols. 



of the 

 Meteorite. 



0-61 

 2-47 

 0-63 



COq 



CO. 



540 

 47-0 

 96 1 



5-0 

 2-0 



42-4 



47-0 



1-5 



3-6 

 l-Q 



The absorption of water and gases evidently went on tolerably 

 rapidly for the first seven days, but after the second heating of the 

 meteorite, its porosity seems to have been affected in some way, for 

 after a further period of eight days, it was found to take up only about 

 a fourth of the quantity of gas which it had absorbed in the previous 

 six days. 



The actual amount of water given off after this exposure to a moist 

 atmosphere was considerably less than what was obtained in the 

 original heating of the meteorite, and from this it was inferred that the 

 water is chemically combined in the stone. It would be difficult to 

 explain, otherwise than by chemical combination, the power by which 

 the water is retained by these meteorites, as it is not given off until a 

 very high temj)erature is reached. In any case it is clear that the 

 hydrogen must come from the action of water on the iron-nickel 

 alloy, or finely disseminated carbon. Greville Williams has pointed 

 out that the large amount of hydrogen obtained from heating finely 

 divided zinc-dust is not due to free hydrogen, but to the action of the 

 zinc on the hydrated oxide of zinc. 



To pass on to the consideration of the various graphites ex- 

 amined. The celestial graphite was a perfect oblong nodule weighing 

 30 grams, which had been taken from the interior of a mass of the 

 Toluca meteoric iron. It had a uniform dull-black colour, except at 

 one end where there was a slight incrustation of sulphide of iron. Its 

 fracture showed a uniform dull-black, compact mass; it was easily 

 pounded up in a porcelain mortar, and formed a fine granular powder 

 without any lustre. 



On extracting the gases from this specimen a considerable quantity 

 of marsh-gas was obtained, so that it appeared most important to 

 compare it with some samples of terrestrial graphites, more espe- 

 cially as the occluded gases had never, as far as the lecturer was 

 aware, been determined in these bodies. 



For this purpose four samples of native graphites were obtained. 

 The Cumberland graphite was a magnificent specimen of the original 

 Borrodale, and had been in a private cabinet for over fifteen years. It 

 had the characteristic dense homogeneous structure and brilliant 



2 N 2 



