16 DEVILS LAKE, NORTH DAKOTA. 
guished in connection with soils: “ Black” alkali, in which sodium 
carbonate predominates, and which is on this account highly corrosive 
and injurious to vegetation; and “ white” alkali, the predominant 
constituent of which is sodium sulphate, and which is much less 
harmful to plant growth. Beth when present in considerable quan- 
tities, by their interference with osmotic action (the process by which 
seeds and plants take up moisture from the soil), prevent or retard 
germination and growth. It will be observed that sodium sulphate 
or “ white alkali ” is the principal constituent of the water of Devils 
Lake. Epsom salts (magnesium sulphate) and common salt (sodium 
chloride) are next in quantity and occur in almost equal proportions. 
Though the analyses here given disclose the presence of alkaline 
salts (not free alkali) in relatively high percentage, it can not be 
assumed that these contained solids in these proportions are neces- 
sarily prohibitive to the acclimatization of certain species of fish. 
The action of this water on introduced fish can be determined by 
experiment; whether it is deleterious has not been fully demonstrated. 
The pebbles and bowlders strewn along the shores of the lake are, 
as mentioned in earlier portions of this report, wholly or partly en- 
crusted with a white deposit of alkali. Nearly all of the surround- 
ing lands, especially the “ dried-up ” bays, show upon their surface a 
_thin grayish-white efflorescence resembling frost. These accumula- 
tions, generally found in regions of deficient or irregular rainfall 
when the soil contains unusually large amounts of soluble salts con- 
centrated in or near the surface, represent the residue from the evap- 
oration of moisture. 
In fact, the scanty vegetation of the lake shores furnishes strong 
evidence of the character of the water. As is well known, alkali lands 
are commonly either entirely devoid of vegetation, or else produce 
plants of little or no value to man. Slowly, but surely, exposed por- 
tions of the basin of the lake are being reclaimed for agricultural 
purposes after a thorough drainage for several years. The presence 
of a small amount of alkaline matter in the surrounding higher lands 
contributes advantageously to the resultant harvest. The more re- 
cently exposed portions of Devils Lake are barren or overgrown with 
a scant growth of wild grasses possessing a marked tolerance to alkali 
and serving as an excellent index, therefore, to the nature of the 
underlying soil. 
Specific gravity—Observations of the density or specific gravity 
of the water were made throughout the period spent by the party at 
Devils Lake, the salinometer and salinometer cup adopted by the 
Bureau of Fisheries being used for the purpose. Fresh water is con- 
sidered as 1.000 on a scale ranging from 1.000 to 1.031, sea water reg- 
istering about 1.025. 
