882 PROCEEDINGS OF THE ACADEMY OF [DeC, 



of collision. It is very natural, therefore, to conclude that some of 

 them must have been caught before they reached the surface of the 

 earth by the outgoing rock fragments and silica which poured out of 

 the hole at the moment of collision. They were doubtless all burning 

 fiercely at this moment, and would have continued to burn, like those 

 which were detached in the upper atmosphere, until all of the iron was 

 converted into magnetic iron oxide, had enough oxygen been present 

 to produce this result. However, some of them seem to have been 

 smothered out when covered up by the silica and the rock fragments 

 included in it. This would perfectly explain why some of them have 

 iron centers and some of them do not possess this peculiar feature, 

 and why the pieces of iron shale continued to rain down for some mo- 

 ments after the collision. An interesting fact which is perhaps worthy 

 of note is, that these iron centers nearly always show a peculiar exuda- 

 tion of drops of moisture, often colored green, partly perhaps from the 

 presence of nickel. This exudation. Dr. Mallet explains to me, is due 

 to the presence of chloride of iron. It is singular, however, that only 

 one of the pieces of meteoric iron which we have, one of those which 

 was found in the trench for the pipe line and is referred to in foot- 

 note 9, exhibits this peculiarity, it being confined to the so-called iron 

 centers, Avhich have only been found in the shale balls which were 

 entirely covered and surrounded by silica and rock fragments. 



During the many visits which I have paid to this remarkable spot, 

 I have made a most thorough search for any other stone than the sand- 

 stone and limestone fragments above described, I have found a 

 number of pieces of flint and some pieces of eruptive rock, but in every 

 case there was every reason to believe they had been brought there by 

 Indians who visited this locality, as many of them were pieces of 

 ' ' matates, ' ' in which the Indians and prehistoric inhabitants of this 

 country ground their corn; and especially because most of them 

 were found in the near neighborhood of the Indian ''hogans" or 

 camps. I had another object, however, than that of trying to find 

 pieces of igneous or eruptive rock, which was to find if possible some 

 pieces of meteoric stone, on the theory that perhaps the great meteor, 

 which by this time I had become firmly convinced produced this 

 crater, was partly metallic and partly stony in composition; in other 

 words, a siderolite. A most careful search of the country for miles 

 around failed to reveal the slightest evidence in favor of this theory. 

 None of the pieces of iron, and by this time several thousands of such 

 pieces have been found on all sides of the crater, have attached to 

 them any particle of stone; except indeed where some pieces of iron 



