430 POPULAR SCIENCE MONTHLY. 



fallen on the earth, also of various kinds of native iron," drew the con- 

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

 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 structure 

 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 1808 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 are now 

 known by his name. Thus the data were early at hand for distinguish- 

 ing meteorites from terrestrial bodies and it soon became possible to 

 collect the 'sky stones' even when they had not been seen to fall. Sys- 

 tematic efforts for the collection of these bodies were not put forth, 

 however, for many years. Up to 1835 there were only fifty-six different 

 meteorite falls represented in the Vienna collection, and in 1856 

 only one hundred and thirty-six. Up to 1860 those of the British 

 Museum collection numbered only sixty-eight and those of the Paris 

 collection only sixty-four. The studies of these bodies during the first 

 half of the century were made, therefore, upon a relatively limited num- 

 ber. The earlier investigations were chiefly chemical in character, vari- 

 ous elements being discovered in succession. Manganese was discovered 

 in the stone of Siena by Klaproth in 1803, chromium in the stone of 

 Vago by Laugier in 1806, 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 discov- 

 ered since has brought the total up to twenty-nine, 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 transparent green mineral accompanying the iron of 

 Krasnoyarsk was olivine. The same mineral was found in other 

 meteorites by later observers, and Eose was able in 1825 to make angu- 

 lar measurements of the crystals which showed them to be identical 

 with those of terrestrial olivine. Laugier separated chromite from the 

 stones of Ensisheim and L'Aigle in 1806. Augite was recognized by 

 Mohs in the stone of Stannern in 1824 and by Eose in that of Juvinas 

 in 1825. Haiiy recognized a feldspar which he thought to be ortho- 

 clase in the stone of Juvinas in 1822, but three years later Eose showed 

 it to be plagioclase; and the existence of orthoclase in meteorites has 

 yet to be proved. Continued investigations of the compounds found 

 in meteorites up to the present time have resulted in the detection of 

 at least twenty-one whose composition is certain, besides several of a 

 somewhat problematic nature. Of these compounds seven have been 



