13 
No. 290 is a peculiar type of soil occurring in the valley on the 
experiment station grounds, and is undoubtedly of sedimentary 
origin, its nature being largely determined by washings from the 
mountain. It is a blue clay soil, exceedingly plastic when wet, but 
upon drying forms hard compact lumps, and is somewhat similar to 
adobe or gumbo soils. This soil also has a soapy feel, and during 
the rainy season aeration and drainage are almost impossible. 
Nos. 405 and 406 are samples of a silty soil, to be found in the 
Kalihi district of Honolulu, which is being used for aquatic agricul- 
ture, the former for rice, the latter for taro culture. 
Nos. 416 and 417 represent the type of red clay soil which is so 
abundant on all the islands. These samples were taken only a short 
distance apart with the view in mind of determining the effect of 
cultivation, 416 being a cultivated soil, while 417 is practically the 
same soil from the unbroken sod. 
Xo. 428 is a sample of highly organic, dark-colored soil from Glen- 
wood, Olaa district, Hawaii. It has a very sandy texture and is 
subjected to heavy rainfall and good drainage, but for some reason, 
probably climatic, is unproductive. 
No. 426 is a sample from Kealia, Kauai, and represents a brown 
type of soil which has partly undergone a recementation of the par- 
ticles into a yellow soft rock, hence the sample contains considerable 
gravel. 
No. 448 represents the type of yellow clay scattered throughout 
the islands in certain districts, this sample having been taken from 
near Hilo, Hawaii. 
The relative solubility of the various constituents is shown sepa- 
rately in order to bring out more clearly the effects of heat, one table 
being devoted to each element. 
silica. 
The following table shows the results obtained in the study of the 
effect of heating on the solubility of the silica: 
Solubility of silica in water and fifth-normal nitric acid. 
[Calculated on basis of dry soil.i 
Soluble in water (parts per million). 
Soluble in fifth-normal nitric acid (per 
cent;. 
Soil No. 
Air dry. 
Dried at 
100° c. 
Dried at 
250° C 
Ignited. 
Air dry. 
Dried at 
100° c. 
Dried at 
250° C 
Ignited. 
74 
35.3 
10.0 
4.2 
2.2 
2.3 
12.5 
2.4 
4.0 
15.9 
1.15 
0.0 
13.0 
2.0 
9.5 
8.3 
2.1 
6.9 
7.8 
10.5 
4.5 
14.9 
3.38 
0.0 
8.7 
3.0 
8.5 
7.2 
17.2 
5.7 
7.8 
9.4 
31.2 
8.9 
7.9 
0.0 
8.7 
4.0 
7. 1 
10.3 
8.6 
16.1 
10.4 
22.3 
33.5 
11.9 
1.13 
8.0 
0. 196 
.007 
. . 15 
.102 
. 150 
.180 
. 005 
.070 
.165 
.289 
.024 
.211 
0.187 
.006 
.091 
.680 
.148 
.219 
.055 
.076 
.173 
.261 
.009 
.226 
0.113 
.027 
.084 
.616 
.264 
.240 
.077 
.097 
.301 
.202 
.062 
.077 
0.225 
164 
.067 
9 
.190 
292 
.523 
290 
.596 
405 
.267 
416 
.192 
417 
206 
ttfl 
428 
426 
.292 
. 320 
.158 
.327 
