XOVEMBER 26, 1900] 



SCIENCE 



IIZ 



It will be noticed by comparing tbese sev- 

 eral analyses that the Pickens County meteor- 

 ite is especially noted for the high percentage 

 of titanium oxide. 



I am indebted to Dr. Oliver C. Farrington, 

 curator of geology, Field Museum of Natural 

 History, Chicago, for the following notes on 

 the microscopic study of a section of the 

 meteorite : 



The meteorite is not ebaraeterized by prevailing 

 chondritic structure. Nevertheless, well-developed 

 chondri are occasionally to be seen in the section. 

 One of these, of circular form with a sharply 

 defined boundarj', consists of fibrous enstatite 

 showing the usual fan-shaped arrangement, and 

 has a diameter of 1 mm. Another chondrus of 

 the same mineral has an irregular boundary and 

 is somewhat smaller. The fibers of this chondrus 

 are characterized by unusual breadth, one being 

 .002.5 of a millimeter wide. Two sets of fibers at 

 right angles are to be seen, giving an appearance 

 of the well-known grating structure of microcline. 

 The fibers also contain granular inclusions ar- 

 ranged parallel to their long axis. Another en- 

 statite chondrus seen is of oval form with diam- 

 eters of .4 and .8 of a millimeter; another of 

 porphyritic chrysolite is marked by an irregular 

 contour and a diameter of .0 of a millimeter; 

 another made up of parallel rods of chrysolite 

 and glass is much smaller, showing a diameter 

 of .2 of a millimeter. The preceding illustrate 

 the principal features and sizes of most of the 

 chondri seen. The remainder of the section is 

 made up of an aggregate of siliceous and metallic 

 grains irregular in size and shape. Few of these 

 have well-defined crystal outlines. Where such 

 outlines appear the parallel extinction and high 

 interference colors show the mineral to be chryso- 

 lite. Irregular fragments of parallel rods of 

 chrysolite and glass of fibrous enstatite which 

 appear here and there suggest that they once 

 belonged to chondri, yet it is possible that they 

 were formed in place. Grains of nickel-iron of 

 various sizes and shapes are very abundant and 

 are disseminated rather uniformly over the sec- 

 tion. One of these of reniform outline is of 

 unusual size, being 2 mm. in length. Inclusions 

 of troilite are to be seen at several points in the 

 body of this nodule. A narrow, dark, opaque bor- 

 der of oxide separates the nodule as a whole from 

 the adjoining silicates. Such individuals were 

 evidently formed previous to the adjacent sili- 

 cates, but most of the smaller metallic grains 



occupy interstices between the silicates, and hence 

 originated subsequent to the latter. These smaller 

 nickel-iron grains are very irregular in form. 

 At times the nickel-iron also occurs in narrow, 

 much elongated, irregular forms suggesting short 

 veins. These likewise have a dark opaque border. 

 Troilite is to be seen in but small quantity in 

 comparison with the nickel-iron. Most of the 

 siliceous grains show a considerable amount of 

 Assuring, the fissures being filled with a dark 

 red liraonite. In addition, the section as a whole 

 shows a rusty staining irregularly distributed, 

 and there is an impregnation in places of a black, 

 opaque, perhaps carbonaceous substance. Tliere is 

 apparently no crust to be seen upon this section. 

 S. W. McCallie 



SOME CONDITIONS FAVORING NITRIFICATION IN 

 SOILS 



Kellerman and Eobinson' have lately re- 

 ported nitrifying tests of North Carolina soils 

 on which legumes were grown, which tests 

 lead to directly opposite conclusions from 

 those reached by Stevens and Withers," who, 

 working with soils from the same state, found 

 that a large percentage of the soils they tested 

 failed to nitrify. Kellerman and Eobinson 

 are further led to believe that " nitrification, 

 nodule formation upon certain species of 

 legumes, and the litmus reaction are cor- 

 related." 



Eesults obtained in this laboratory indicate 

 that nitrification is favored by an increase in 

 the basicity when the soil is deficient in lime. 

 Our experiments further indicate that the 

 growth of alfalfa on the soil favors nitrifica- 

 tion, or, at least, increases the availability of 

 the soil nitrogen. 



Nitrification tests on samples of soil from 

 four limed and four unlimed plats averaged 

 twice as great an increase in nitrates on the 

 limed soil as the result of a ten-day test, and 

 tripled the nitrate production in a three-week 

 test as a result of incorporating lime with the 

 soil in the field. The lime was added four 

 years before the tests were made. 



The increased production of nitrates on 

 alfalfa soil as compared with a perennial non- 

 legume was not so striking, but the favorable 



' Science, N. S., XXX., No. 7G9, p. 413. 



= Science, N. S., XXIX., No. 743, p. 50G. 



