evolved on heating Mineral Substances, Meteorites, &c. 1:39 



G-as in 



volumes'of 



meteorite. CO 2 . CO. H 2 . N 2 . 



After 24 hours 0'61 54'0 42'4 3-6 



After 6 days more ... 2*47 47'0 5'0 47'0 1*0 



After 8 days more ... 0'63 96'1 2*0 1-5 



The quantity of water reabsorbed after the second heating was very 

 small, and it is interesting to note that the quantity of hydrogen 

 evolved during the subsequent heating was also very small. From 

 this it would appear that the hydrogen was produced directly from the 

 water. There is no evidence to show whether the carbon dioxide 

 -entered into combination with some constituent of the meteorite, or 

 not. 



Meteorites of the second class usually consist chiefly of metallic iron, 

 nickel, &c., with small quantities of crystalline minerals, such as 

 olivine. The presence of these minerals, which are usually hydrated 

 silicates containing ferrous oxide, might in themselves account for the 

 formation of hydrogen. The carbon monoxide might be produced by 

 the interaction of carbon dioxide, the product of decomposition of a 

 -carbonate, with the metallic iron. The small quantities of hydro- 

 carbon, which are also present in the gas, and which appear to belong 

 to the saturated series, might be produced by the action of water, 

 which is invariably present, upon metallic carbides. The changes 

 which take place are probably of a complicated nature. 



In order to ascertain whether a sample of meteoric iron actually 

 contained occluded or enclosed gases, the following experiment was 

 performed. A piece of meteoric iron was cut into fine shavings, which 

 were carefully cleaned. The metal was divided into two portions ; one 

 part was heated in a sealed tube with copper sulphate and water, in the 

 manner already described, the other was heated in vacua. The gases 

 evolved were in each case collected and analysed. 



Copper 

 sulphate 

 By action of heat. experiment. 



Hydrogen 0'322 c.c. per gram "I Q.QI 4 



Carbon monoxide and hydrocarbons... 0'164 J 

 Carbon dioxide 2'222 0'739 



The trace of hydrogen which was produced during the copper 

 sulphate experiment may well be attributed to secondary relations 

 between the metal and the salts in solution. 



It would appear then that the gases produced by the action of heat 

 upon meteorites are not present as such, but are the products of decom- 

 position of their non-gaseous constituents. It is therefore impossible to 

 draw conclusions as to the former history of a meteorite from the 

 nature of the gases which it gives on heating. 



M 2 



