SII>i;i;()LITK. 07 



the process takes place slowly and gradually. They appear to me to sliow that meteoric 

 iron was kept for a long time at a heat just below the point of fusion, and that we 

 should be by no means justified in concluding that it was not previously melted. Similar 

 principles are applicaljle in the case of the iron masses found in Disco ; and it by no 

 means follows that they are meteoric, because they show tlu Widmanstatt'.s figuring. 

 Difference in the rate of cooling would serve very well to explain the difierence in the 

 structure of some meteoric iron [s], which do not differ in chemical composition ; but as 

 far as the general structure is concerned, I think that we are quite at liberty to conclude 

 that all may have been melted, if this will better explain other phenomena." * 



It would appear tliat these observers advocate the view that the sidero- 

 lites must have been subjected to a long and slow cooling upon some body 

 of sufficient size to yield the required conditions ; but since the same struc- 

 ture can be developed in the iron of the stony meteorites, which show evi- 

 dence of rapid cooling, the writer is compelled reluctantly to differ from 

 these eminent observers, and to hold that while the Widmannstiittian figures 

 may have originated as they have claimed, they may occur as readily in a 

 small mass, cooling at a comparatively rapid rate, and therefore their origin 

 is to be explained in some other way. In other words, as yet, there is no 

 evidence that Sorbj^'s and Tschermak's views are correct. 



It is probable that but few will claim that the siderolites of meteoric 

 origin were formed by organic agencies. If they were not, it follows that 

 the graphite contained in them could not have been so produced. This has 

 a very direct and obvious bearing on the question whether the graphite in 

 Azoic and other rocks need have been derived from animal or plant remains, 

 and it negatives the supjDOsition.f 



To make graphite the evidence of life is the same kind of argument as it 

 is to claim that no oxides of iron and no carbonate of lime could be formed 

 w^ithout the intervention of life. One we knew to be oftentimes of volcanic 

 origin, and the other to be frequently the product of the decomposition of 

 rocks. It is too much to assume, because minerals are known to form in 

 certain conditions, or can be formed in certain ways, that they must always 

 be made in that way. None of the meteorites now known appear to indi- 

 cate that the}^ came from a region where life could exist as we know it ; 

 hence, it does not seem proper to claim that life must have intervened in 

 their formation merely because a mineral is found in them that is ordinarily 

 supposed to be of organic origin. 



* Nature, 1877, xv. 498. 



t J. Lawrence Smitli, Mineralogy and Chemistry, 1873, pp. 2S-4-310; Am. Jour. Sci., !$?() (o), xi. 3SS- 

 395, 433-442 ; Walter Flight, Pop. Sci. Rev., 1877', xvi. 390-401. 



