1<)4 CENTURY OF STUDY OF METEORITES. 



matter not of terrestrial origin does at intervals come to the earth. 

 Since this beginning the study of meteorites has been one of constantly 

 widening interest and purport. 



The essentially distinguishing features of meteorites were early 

 made out. Howard in L802, from a chemical investigation of various 

 "stony and metallic substances which at different times are said to have 

 fallen on the earth, also < >f various kinds of native iron." drew the con- 

 clusion that a content of nickel characterized most such bodies. lie 

 also found that the meteoric stones were made up chiefly of silica and 

 magnesia and that the iron sulphide of meteorites was distinct from 

 the terrestrial mineral pyrite. He further noted the chondritic struc- 

 ture as characteristic of many of the meteoric stones. The correctness 

 of his observations was soon confirmed by analyses made by Fourcroy, 

 John, Klaproth, and others. In L808 Alois von Widmanstatten, by 

 heating a section of the Agram iron, brought out the figures which 

 have since proved so characteristic of meteoric irons in general and 

 which arc- now known by his name. Thus the data were early at hand 

 for distinguishing meteorites from terrestrial bodies, and it soon 

 became possible to collect the "sky stones" even when they had not 



been seen to fall. Systematic efforts for the collection of these bodies 

 were not put forth, however, for many years. Up to 1835 there were 

 only 56 different meteorite falls represented in the Vienna collection, 

 and in L856 only L36. I'}) to 1860 those of the British Museum col- 

 lection numbered only 68 and those of the Paris collection only 64. 

 The studies of these bodies during the first half of the century were 

 made, therefore, upon a relatively limited number. The earlier inves- 

 tigations were chiefly chemical in character, various elements being 

 discovered in succession. Manganese was discovered in tl e stone of 

 Siena by Klaproth in L803, chromium in the stone of Vago by Laugier 

 in L806, carbon in that of Alais by Thenard in 1808, chlorine in that 

 of Stannern by Scheerer in the same year, and cobalt by John in the 

 Pallas iron in 1817. The number of elements discovered since has 

 brought the total up to 29, none being found, however, which are not 

 already known upon the earth. Many of the chemical compounds of 

 meteorites were early isolated and their identity with terrestrial 

 minerals established. Count Bournon showed in 1802 that the trans- 

 parent green mineral accompanying the iron of Krasnojarsk was 

 olivine. The same mineral was found in other meteorites by later 

 observers, and Rose was able in L825 to make angular measurements 

 of the crystals which showed them to be identical with those of ter- 

 restrial olivine. Laugier separated chromite from the stones of 

 Ensisheim and L'Aigle in L806. Augite was recognized by Mohs in 

 the stone of Stannern in 1824 and by Rose in that of Juvinas in 1825. 

 Hauy recognized a feldspar which he thought to be orthoclase in the 

 stone of Juvinas in 1822, but three years later Pose showed it to 



