132 On the Tchornoi Zt 



fSUica . . . 71-56 



Insoluble in boil- ] I Alumina . . C"36 



iiig hydrochloric >79' 30 j Lime (traces ofj 



acid J I Magnesia . . O'2-l 



or according to the quantities J Earth. Org. matter. Incombustible. 10*237 soluble. 



used in the analysis^ tl-724= 0- 119 -f 1-605 j 1-368 insoluble. 



After detailing the minute proportions of these soluble and insoluble contents, M. 

 Payen adds, that the analysis of the combustible organic matter indicated the presence 

 in 100 parts of the original earth, of . Water 4- 81 



Azote 2-45 



7-26 

 4- 140 grammes of the earth yielding 9* 498 cuhic centimetres of azotic gas. * 



In order to avoid error, not pretending myself to be acquainted 

 with the method of analysis employed by M. Payen^ I here refer 

 my readers to the original document, j 



* If we only consider the diemical elements of which this black earth, 

 which is stated to be so fertile, is composed, the analysis does not afford us 

 much information, without a knowledge of its mechanical texture. The 

 same elementary substances may be so variously combined as to produce 

 very different soils in respect to fertility. Thus, if 70 per cent, of silica 

 were in the form of small crystals, such as we find in sea-sand, and the 

 13 per cent, of alumina combined with the 7 per cent, of iron and the sul- 

 phuric acid were mechanically mixed with the sand, the result would be a 

 soil not much superior to that of Bagshot Heath ; and although the 6 or 7 

 per cent, of organic matter, especially with a considerable portion of animal 

 matter, would give it some fertility, it would never be fit for the growth of 

 wheat, from a want of firmness. JBut if the alumina is combined with the 

 silica, so as to form clay, and a portion of the silica only is in the form of 

 fine sand, making with the clay a loamy soil, and the oxide of iron be a 

 peroxide not hurtful to vegetation, then the organic matter intimately mixed 

 with this soil will form the richest wheat-loam. This confirms an opinion I 

 have ventured to express elsewhere — that, when the silica is in a very high 

 state of division, and intimately blended with the alumina, it can no longer 

 be considered as sand ; nor has it the porous quality by which sand is soon 

 deprived of its moisture, and the organic matter is exhausted in it. This 

 shows the necessity of a mechanical examination of a soil, which is so easily 

 effected by sifting and washing alone, conjointly with an accurate chemical 

 analysis, before we can form a correct opinion of the real fertility of a 

 soil. — W. L. Rham. 



t Analyse de la Terre Noire de Russie, sur un C-chantillon transmis par M. Gourieff. 



Analyse. 

 6 • 95 mat. organique combustible. fAlumine . = 5-04 



100 terre —I c< i 1 1 i t n i i Ox. de fer . = 5 '62 

 no A' 1 /Solubles dans lac. chloihvd. I ^, „ "^ 



93-Ooceudres .{ , ;ii„.,^ _ lo.^n • < Chaux .= 0-82 



Magnesie . = 0*98 



Chls. alcals. = 1-21 



rSilice . . = 71-56 



[nsolubles dausTac. chlorhyd.j Alumine . = 0-36 



bouillant = 79-o0 j Chaux (traces). 



iMagnesie . = 0-24 



Ou d'apres les quantites employees pour I'analyse 1 -721 10- 237 soluble, 

 terre = 0-119 mat. org. + 1-605 ceudre = . , j 1-308 insoluble. 



bouillant s= 13-79 



