CITRIC-SOLUBLE PHOSP110RIC ACID AND POTASH. 9 
In the case where large samples (25 grams) of slag and feldspar 
were used the resulting solutions differed but little in respect to their 
potash content, but considering the fact that the sample of slag con- 
tained less than one-half as much potash as the feldspar, the per- 
centage of potash dissolved from the former was nearly four times 
as great. Moreover, while no quantitative determinations were made 
of the total solids in solution, the amount dissolved from the slag 
was apparently many times greater than that dissolved from the 
feldspar. 
In the case where only 0.25 gram samples of the two substances 
were used the slag yielded a solution nearly three times as strong 
(in respect to potash) as the feldspar, and when the quantity of 
potash in the two substances is considered the percentage dissolved 
from the slag was nearly seven times greater. 
RESULTS OF POT TESTS WITH SLAG FERTILIZER. 
Although the solubility of the potash and phosphoric acid in the 
slag product was indicative of its agricultural value it was thought 
advisable to test its merits by actually growing plants in soils treated 
with this material, and comparing their growth with that of plants 
grown under similar conditions in the same soils untreated and 
treated with well-known potassic and phosphatic fertilizers. 
The experiments were conducted by Mr. J. J. Skinner of this 
bureau. The wire-basket method described in Circular 18, Bureau 
of Soils, was employed, using wheat seedlings. 
Three types of soil were used, namely, the Carrington silt loam 
from Wisconsin, the Hagerstown loam from Pennsylvania, and the 
Volusia silt loam from New York. These soils are described in 
Bulletin 96 of this bureau as follows: 
The Carrington silt loam consists of a dark-brown to black silt loam, having 
an average depth of about 12 inches. The subsoil is a yellowish-brown to pale- 
yellow silty clay loam or silty clay. The topography is mainly level to undu- 
lating. The soil represents a residual stratum derived from glacial till. The 
type is admirably adapted to the general farm crops, including wheat, corn, 
oats, barley, rye, flax, and grass. 
The Hagerstown loam is a brown or yellow loam averaging about 12 inches 
in depth. The subsoil is a yellow or reddish clay loam to a depth of 24 inches, 
but frequently grades into a stiff, yellowish-red clay. The type occupies rolling 
valley land, and is derived from the weathering of pure limestone. This is 
typical corn soil. It is one of the best general farming types in the eastern 
States, and is used for corn, tobacco, wheat, grass, and apples* 
The soil of the Volusia silt loam, to an average depth of 8 inches, is a gray to 
brown silt loam. The subsoil to a depth of 2 feet is a light-yellow silt loam, at 
which point mottlings of gray or drab are encountered. Both soil and subsoil 
