62 II L. Preston — Iron Meteorites^ as nodular 



With the exception of number 2, the negative for which 

 showed only nine sparks, the manganine and German silver 

 wires gave practically the same number of oscillations, namely 

 5, and we may conclude that there is no surface travel in their 

 case. With the iron wire there is a marked " skin effect," 

 owing doubtless to the large value of /x. 



An examination of Plates III and IV, the most reliable 

 results, shows that the points on the solution-curves unques- 

 tionably tend to fall below those on the wire curves. The evi- 

 dence is, then, in favor of a surface travel in the electrolyte. 



It is intended to carry this investigation further along the 

 same line, for it seems very likely that, with an apparatus giv- 

 ing a higher period, the existence of a surface travel in elec- 

 trolytes can be completely established. 



Jefferson Physical Laboratory, Harvard University. 



Art. XI. — On Iron Meteorites, as nodular structures in 

 Stony Meteorites ; by H. L. Preston. 



[Read before the Rochester Academy of Science, Nov. 9th, 1897.] 



It is an important fact that of over one hundred falls and 

 finds of siderites or iron meteorites but nine have been seen 

 to fall, while of the aerolites or stony meteorites of over four 

 hundred falls and finds, some two hundred and sixty, or more 

 than one-half, have been seen to fall. 



Does this imply that during earlier centuries, the iron 

 meteorites were more prevalent than at the present time, and 

 vice versa, that during the present, the aerolites are more preva- 

 lent than during the past ? This seems improbable, and the 

 writer will present in this paper some suggestions as to the 

 origin of iron meteorites that have occurred to him while 

 handling many scores of these interesting objects. 



In the first place, all the nodular masses of the iron meteor- 

 ites, known as siderites, are believed to be of the same nature 

 as the small specks, or grains of iron that occur in all the stony 

 meteorites, these nodules being, at one time, surrounded by a 

 magma or ground mass of stony matter, as are the specks of 

 iron in the aerolites. 



In all igneous rocks, where there is a concretionary structure, 

 we know that the slower the cooling the larger the concretions; 

 for when in a molten state, solidification commences at cer- 

 tain points. The slower the cooling, the greater amount of 

 material gathered around these nuclei, or points of solidifica- 

 tion. The law of molecular attraction — the affinity that an 



