160 TENTH ANNUAL REPORT OF 



mark that no one of them is associated with oxygen, although all of 

 them have a strong affinity for this element, and are never found (except 

 copper) in the earth uncomhined with it, except where some similar 

 element (as sulphur, &c.) supplies its place. 



The inference of the absence of oxygen in a gaseous condition, or in 

 water, is drawn from such substances as iron and nickel being in their 

 metallic state, as has been just mentioned ; but it must not be inferred 

 that oxygen is absent in all forms at the place of origin of the meteor- 

 ites, for the silica, magnesia, protoxyd of iron, &c., contain this 

 element. The occurrence of one class of oxyds and not of another 

 would indicate a limited supply of the element oxygen, the more oxyd- 

 izable elements, as silicon, magnesium, &c., having appropriated it in 

 preference to the iron. 



Many other elements worthy of notice might be mentioned here, 

 and some of them, for aught we know, may be constant ingredients ; 

 but in the absence of strong presumption, at least, on this head, they 

 will be passed over, as those already mentioned suffice for the support 

 of the theoretical views to be advanced. 



I cannot, however, avoid calling attention to the presence of carbon 

 in certain meteorites ; for although its existence is denied by some 

 chemists, it is nevertheless a fact that can be as easily established as 

 the presence of the nickel. The interest' to be attached to it is due to 

 the fact that it is so commonly regarded in the light of an organic 

 element. It serves to strengthen the notion that carbon can be of 

 pure mineral origin, for no one would be likely to suppose that the 

 carbon found its way into a meteorite, either directly or indirectly, 

 from an organic source. 



Having thus noted the predominant physical, mineralogical, and 

 chemical characteristics of meteorites, I i)ass on to the next head. 



Harked points of similarity in the constitution of meteoric stones. — 

 Had this class of bodies not possessed certain properties distinguishing 

 them from terrestrial minerals, much doubt would even now be enter- 

 tained of their celestial origin, even in those cases where the bodies 

 were seen to fall. But chemistry has entirely dissipated all doubts 

 on this point, and now an examination in the laboratory is entitled 

 to more credit than evidence from any other source in pronouncing on 

 the meteoric origin of a body. When the mineralogical and chemical 

 compositions of these bodies are regarded, the most ordinary observer 

 will be struck with the wonderful family likeness presented by them 

 all. 



There are three great divisions of meteoric bodies, namely: metallic ; 

 stony, with small particles of metal ; and a mixture of metallic and 

 stony in which the former predominates, as in the Pallas and Atacama 

 meteorites. The external appearances of these three classes differ in 

 a very marked manner ; the meteoric iron being ordinarily of a com- 

 pact structure, more or less corroded externally, and, when cut, show- 

 ing a dense structure with most of the peculiarities of pure iron, only 

 a little harder and whiter. The stony meteorites are usually of a grey 

 or greenish grey color, granular structure, readily broken by a blow 

 of the hammer, and exteriorly are covered with a thin coating of fused 

 material. The mixed meteorite presents characters of both of the 



