Soil No. 292. This type of soil occurs in the lowlands in and about 
Honolulu, now being used for growing bananas, rice, and for truck 
farming. It has a sandy texture, being partly derived from black or 
volcanic ash. It has a grayish-brown color, abnormally high mag- 
nesia content, and low content of organic matter. 
No. 448 represents the type of yellow clay scattered throughout 
the islands, this sample being taken near Hilo, Hawaii. 
No. 428 is a dark colored, highly organic soil from Glenwood, 
Hawaii. It has a very sandy texture, is subject to heavy rainfall, 
and is rather unproductive. 
No. 474 is a sample of soil from Parker ranch, Waimea, Hawaii. 
It is a brown-colored soil of floury texture and very productive. 
No. 517 represents the type of soil which is most abundant in the 
islands, namely, the heavy red clay, a highly ferruginous type. 
METHOD. 
The method of treatment adopted in this investigation was as fol- 
lows: 100 grams of air-dry soil was placed in glass tubes, 1 inch in 
diameter, and fitted with rubber stoppers and pinchcock to regulate 
the passage of the solution through the soil. The percolation was regu- 
lated to flow at a rate of 100 cubic centimeters in 24 hours, and each 
successive 100 cubic centimeters of percolate was analyzed. The salts 
used were sodium nitrate, potassium phosphate, and calcium phos- 
phate, separately and as a mixture. One series was also heated to 
230° C. and another treated with chloroform to determine the effect 
of these agents upon absorption. All determinations were made- by 
colorimetric methods, except those of potash, which was precipitated 
and weighed as potassium chloroplatinate. 
ABSORPTION OF PHOSPHORIC ACID. 
In this series the percolation was carried on for nearly two months, 
5 liters of the solution of potassium phosphate passing through the soil. 
The solution used contained about 200 parts phosphoric acid (P0 4 ) 
per million, and each time a new solution was made up the strength 
was determined by analysis. Owing to the fact that percolation 
through a column of the soil was found to be impossible, due to the 
strong deflocculating effect of this salt, the percolation in this series 
was carried on in funnels. Even then several of the samples filtered 
very slowly. The filtrate from the clay soil was very cloudy, and the 
percolates became slightly stagnant in several instances after the 
percolations had been carried on for about one and a half months. 
In order to get a clear conception of the fixation of phosphates 
it is necessary to have some idea of the solubility of phosphoric acid 
already present in the soil when treated in the same way as in the 
