1905.] NATURAL SCIENCES OF PHILADELPHIA. 907 



were at the levels at which most of the other meteoric material was 

 found, the first water drawn from the hole in the morning, after stand- 

 ing over night, was found to contain a very considerable amount of 

 dingy green protoxide of iron suspended in it, which upon exposure to 

 the air rapidly oxidized and became converted into a reddish-brown 

 hydrated sesquioxide. The only explanation that can be offered for 

 these phenomena is that, probably, the extremely thin films of silicate 

 of iron have had their iron dissolved by long immersion in water con- 

 taining carbonic acid, leaving their gelatinous silica skeletons suspended 

 in the water, and that the solution of carbonate of iron may later have 

 lost its carbonic acid in some way, possibly by absorption by lime from 

 the limestone strata, and precipitated out of the protoxide of iron which 

 remains in suspension in the water. It has also been noted that from 

 the deeper portions of the hole, below 600 feet, where the meteoric 

 material has not been found, that the sand itself showed a very minute 

 trace of nickel, which has probably come from the leached meteoric 

 material above it.^ 



The Possible Encounter of Larger Meteoric Material. 



The small prospecting shafts above referred to were stopped by 

 water at 200 feet before penetrating to levels at which later explora- 

 tions showed the meteoric material was to be encountered.- This 

 stoppage was caused by their small size and their light timbering, which 



' Since this article was written, the author has discovered the presence of a 

 small amount of very finely divided metallic iron among the silica. This has 

 been found, so far, in every sample examined, from the north and south rims as 

 well as from tlie filling of the central plain. It varies in amount, but its propor- 

 tion is extremely small. The largest amount has been found among the silica 

 from the filling of the crater, where it exists to the proportion of nearly a quarter 

 of an ounce to the ton. From the north and south rims the amount is less in 

 the order stated; from the south rim it does not amount to a twentieth as much 

 as from the interior of the crater. 



This metallic iron was detected, separated and estimated as follows: The 

 silica was passed through a magnetic separator and a very small amount of mag- 

 netic material of a dark color collected and weighed. A weighed portion of this 

 was carefully ground in an agate mortar, wet and the finely powdered material 

 washed away from time to time until the material was reduced to about one- 

 tenth of its original bulk. In this residue, by the use of a glass, could be ob- 

 served a great number of bright, white, shining metallic scales and spangles. 

 The}'- were strongly influenced by a magnet. A solution of copper sulphate was 

 then poured over this residue and the bright white spangles were observed to 

 turn dull red-copper color at once. The finer portions were then observed to 

 be indifferent to the magnet, although the larger ones were still attracted. On 

 prolonged treatment all became indifferent to the magnet. The residue was 

 then washed and the copper in it determined, there being none in it before 

 treatment. As a check the iron was determined in the copper sulphate solu- 

 tion used and wash waters, the solution being pure. Distinct traces of nickel 

 were also observed in this material. 



