E. W. Hilgard—Soit Analyses and their Utility. 441 
Very pars RE ewiivecwe 1°5 to e: bs per: cent, 
MORI BOBS sian i 5°0 to 
Clay De very heavy, .--....,.12°0 to 1 : 
there being, of were all serie grades of hygroscopic 
power, as we of ‘heay t appears that for this 
mterval of ‘eepenibens: the peomaiarte of absolute absorbing 
power in the soil, resulting from the rise of temperature, is 
just balanced by the increased amount of vapor diffused in 
the air—not an unimportant circumstance, with regard to 
vegetable life. 
There are, however, two soil ingredients which interfere 
seriously with the correctness of the estimate as to Pama 
erived from the coefficient of absorption, viz., “humus” an 
Jerric oxide. Both of these are highly hygroscopic, ye both 
counteract the ‘‘ heaviness” caused by excess of clay. Moreover, 
there is a class of soils (viz, fine siliceous silts) whose exceeding 
“heaviness” in cultivation is much complained of, yet whose 
absorbent — is very sm 
When, as in the majority ree cases, the surface soil has none 
tm derived from the subsoil, the disturbing effect of the 
umus” may be sensibly eliminated by comparing, not the 
soils, fee the subsoils, in this respect.* As to the ferric oxide, 
there are among about 200 Mississippi soils analysed but three 
or four whose agricultural qualities would have been seriously 
- earaame cates by a reliance upon the coefficient of absorption 
a 
But I do not for a moment admit, that in a material so com- 
= both in its composition and mode of action any one or 
_ data, whether chemical, — or ec mango may be 
e soil: or, as Prof. Johnson ex- 
orate it, ‘to do violence to agriculture.” So far from this, 
consider that a proper interpretation of the analytical veal 
must take into ee not only all the chemical an 
physical facts observed on the specimen, but all that has been 
or can be observed in loco—the location, _ a 
relations to drainage, ete. ; as well as all that i s known co 
a earches ssippi, ra sixteen years past. 
C early, the oie Ai pets : Prof Johnson’s position and 
mine is one of degree only ; yet this difference is not a slight 
* In such cases, the surface soil is always more sandy than the subsoil. 
Am. Jour. oo se Vou. 1V, No. 24—Drc., 1872. - 
