244 METALS TN THE ATMOSPHEKE. 



high temperatures. Iron is also found in seniitraiispareiit. masses, 

 green, yellow, or pink, mixed with opaque black particles. These 

 M. Stanislas Meunier believes to have come from the dehris of ser- 

 pentine minerals — diorite, amphibolite, serpentine — containing gran- 

 ules of magnetite and always rich in oxidized iron. 



But this terrestrial source of ferruginous dusts can not exphiin the 

 extraordinary abundance of microscopic ])articles of iron found in 

 polar and alpine snows and in rains collected in open country. The 

 presence of this nickel-bearing iron dust can be explained only as a 

 powder obtained from the surface of meteorites in the ways we have 

 shown. 



Metah other than iron. — It follows, then, that iron is the metal 

 most abundant in the air, and that in t'very case when its origin is 

 extraterrestrial it is associated in variable proportions with nickel 

 and cobalt; l)ut there are also other metals in the atmosphere. The 

 analysis of their cinders, as already mentioned, show^s that they are 

 com])os(Ml of some substances soluble in water, others soluble in hydro- 

 chloric acid, and some insoluble. The almost white sediments col- 

 lected in the fields contain about 40 per cent of salts soluble in water, 

 80 \)vv cent of such matter as calcium and magnesium carbonates, 

 oxide of iron, and some insoluble substances like silica and clay, with 

 small quantities of carbon. 



An examination of the dust deposited in the towers of Notre Dame 

 gave 67 per cent mineral matter, 9 per cent of which was soluble in 

 water, 23 per cent soluble in hydrochloric acid (this decomposing 

 into ().l per cent sesquioxide of iron, 10 per cent calcium carbonate, 

 and 2.1 per cent magnesium carbonate, with traces of aluminum and 

 phosphorus), and ot.3 per cent of matter, principally silica, not solu- 

 ble in the acids. A grayish powder, line and soft as meal, collected 

 at Boulogne on October 9, 18TG, contained in a dry state, besides 9.7 

 p(>r cent of organic substances, 55 per cent of silica, 1.8 per cent alumi- 

 num (with traces of iron), 30.() per cent calcium cai'bonate, and 2.5 

 j)er cenl magnesium carbonate. In the ash calcium, ahnninum, mag- 

 nesium, and other metals were also found. 



Besides theii- two principal components- -iron and nickel — meteor- 

 ites and their debris contain small ^■a^ia!)lc (juantitics of cobalt, man- 

 ganese, chrome, tin. magnesium, and ahnninum. Some minerals in 

 [)articular are contained in these bodies: Schi-eibci'site (phosphide of 

 ii'on and nick'cl), magneiitc and chrome iron, which is sometimes 

 found in considei'able (|uantilics in the foi'ni of tiny grains, and 

 niiinite cr\stals, logellici' with olixinc and other silicates. In shorty 

 meteorites may be arrangetl in a h»ng -series, at one extremity of which 

 are those c()m{)osed chiefly of iron and nickel and at the other chiefly 

 nomnctallic mineral substances, a^ oli\'ine, enstatite, feldspar, amphi- 



