Geological Surveys of Kentucky and Arkansas. 241 
tury of wheat crops would remove, likewise consists of twelve 
ingredients, 
The 2d result of these analyses, according to Drs. Owen and 
Peter, is what the former (4th Ky. Rep., p. 38) declares to be 
“a general law” ‘now established,” viz., ‘that soz-analysis ts 
capable of showing the exhaustion in land of the mineral food of 
plants by continual cropping.” 
To show the removal of soil-ingredients by cropping, the 
plan was followed of collecting soils from contiguous fields, one’ 
of which had been “cultivated” while the other was in its virgin 
acid. Soils 1207 and 1208 by 0°033 per cent potash. Similar 
fractions likewise show the amount of deterioration in the other 
Seventy-one cases. We adduce two instances ointed out by 
Dr. Peter in the 3d Kentucky Report, p. 207, and one given on 
P. 176 of the 24 Arkansas Report: 
Carb. of lime. Magnesia. Phosphoric acid. Potash. 
Virgin soil, No. 557, 0°345 0" 181+ "156 
Old soil, No. 558, | 0-215 0465 —— 0°103 0101 
Difference, 0°130 0°130 gain. 0-07 0°055 
Virgin soil, No. 738, 0-180 0°44 0-179 0256 
Old field, No. 739, 0-145 —«0°388 0163  Or179 
Difference, 0°035 0:056 0016 0:077 
Viteis-aci ; 0371. «0127 0-116 
0 rgin soil, No. 288, 0°121 ious eter 
Id field, No.289, 0-021 0871 ) 
Difference, "0-100 0-000 0-074 0-019 — 
other by an amount equal to the quantities upon whic 
“natural law” is saspanad, we assert what every competent 
* Misprinted twenty- 81, 4th Kentucky Report. . 
+ Mixprinted oer 007, Ba RY: Rep, where the difference 1s made 0°045 instead 
of 0078, as given above from the tabulated anal 
Am. Jour. Scr.—Szconp SERIES, VOL. 
31 
