196 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



to a brown glass on its thin edges. A very small splinter in 

 the reducing flame acquires at first a dark color, and then 

 fuses to an almost colorless glass, dotted with dark spots. 

 This experiment shows the phases in the change of the surface 

 of the stone from its normal to a vitrified condition. Heating, 

 as usual in experiments on metamorphism, also indicates that 

 the crust is simply a metamorphosed, not a fused, mass. The 

 thinness and. regularity of the crust are explained as doubtless 

 being due to the exceedingly low temperature of the stones 

 at the moment they strike the earth's atmosphere. To this 

 same excessive cold must be ascribed the cohesion of the car- 

 bonaceous meteorites which penetrate the earth, or rebound 

 from it at their fall, while, under ordinary circumstances, 

 they fall to pieces under the least blow. 

 Perhaps a study of the metamorphosis of meteorites will 

 reveal an aiDproximate measure of the temperature of the in- 

 terplanetary space, in regard to which there are such contra- 

 dictory estimates ; and the thickness of the metamorphosed 

 crust, which is independent of the size of the stone, may pos- 

 sibly, by means of a few readily suggested experiments, give 

 us an indication of the internal temperature of the stones 

 when suddenly exposed to the effects of heat, from which 

 the temperature of the regions whence they came may be de- 

 rived. ' 



The form of the meteorites, and especially the evident con- 

 trast between the front and back parts, are generally con- 

 strued as arguments in favor of the action effusion in the 

 formation of the crust ; but the facts already given completely 

 contradict the opinion that the matter has been melted away 

 from the blunt edges, as the temperature necessarily implied 

 would have left its impress in the mass of the stone, while 

 many decidedly rounded meteorites have remained perfectly 

 white for example, that of New Concord, in May, 1860, 

 This rounding of the front face seems due to erosion by the 

 air, as truly as that of rocks to erosion of w^ater. The fur- 

 rows and folds are the result of sculpturing, and the crust is 

 produced in the bared portions in proportion as the heat 

 penetrates. According to this view, many meteorites man- 

 ifest a striking general resemblance to some Scandinavian 

 islands, scraped out by glaciers on the north, while they have 

 been protected on the" south. 19 (7, October 26, 1872, 352. 



