8 BULLETIN 6 2, HAWAII EXPERIMENT STATION 
material. Because of these and certain other conditions, the soil 
reaction also varies considerably from the acid upland kinds to the 
neutral and alkaline calcareous or saline kinds of lower levels. 
On the basis of the preliminary analysis given in the Appendix, 
some 21 soils were selected for the main part of the investigation. 
The selection was made primarily with regard to origin, appearances, 
and physical characteristics, and secondarily, on the basis of agri- 
cultural adaptability. A few of the samples are not typical or 
representative of larger areas, but were included because they pos- 
sessed some unusual property especially in so far as colloids are con- 
cerned. Of these 21 soils, 13 came from agricultural, and 8 came 
from nonagricultural districts. The description of the character 
and nature of the soils follow. 
Soil No. 2 is a clay from Lanikai, windward Oahu, near the sea 
at sea level. It closely resembles the adobe type of soil and is allu- 
vial in origin, the fine clayey material having been washed down 
from the surrounding mountain slopes. This is a very plastic and 
sticky light-brown sodium clay of low organic content. Vegetation 
does not do well in this soil on account of the deflocculated condition 
of the clay. 
Soil No. 6 is a clay from Salt Lake Crater, Moanalua, near Hono- 
lulu, where the Twin Salt Lakes are located. Originally a lake bot- 
tom of saline nature, this area was reclaimed for agriculture by 
draining and covering with fertile loam from other localities. How- 
ever, agriculture (sugarcane production) had to be abandoned be- 
cause of the high alkalinity and high clay content of the soil. It 
is a very sticky and plastic gray clay of low organic content and 
high specific gravity. 
Soil No. 9 is a clay loam from near the Pearl City Peninsula, Oahu, 
very near the ocean (Pearl Harbor), at sea level. This is a light 
gray, pulverulent light clay, of the type used in rice culture. It is 
black when moist on account of the large content of humus and 
partly decomposed organic matter accumulating under anaerobic 
conditions. The soil is very acid in reaction and has the lowest 
specific gravity on record in the station laboratory. The clay is in 
a perfect state of flocculation, due to the flocculating effect of the 
large amount of electrolytes present. 
Soil No. 12 is a sandy clay loam from field 4-5, section F, in the 
Mountainview section of Olaa plantation, Hawaii. Eesidual in 
origin, this light-brown mountain soil of low clay content contains 
large amounts of undecomposed and partly decomposed organic 
matter existing under semianaerobic conditions. The soils of this 
district (Nos. 10 to 14, inclusive) are characterized by high moisture- 
absorbing and moisture-holding capacity. Forming under excessive 
rainfall where drainage is poor, these soils are always water-logged. 
The surface soils are dominated by a large amount of organic mat- 
ter, whereas the subsoils are light-drab or light-brown mottled 
putty like clays. The lava from which they have been formed, 
according to Burgess (10, p. 58) , is at a depth of 2 to 3 feet. Some 
of these soils will hold four to five times their weight in water. In 
the station laboratory soil No. 11 had a moisture content of 411 per 
cent and soil No. 13 a moisture content of 500 per cent. (See also 
Shaw, 33, p. 4&0.) Agricultural operations are carried on with 
