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. Both 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^ ujDon 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 w^ater is con- 

 sidered as 1.000 on a scale ranging from 1.000 to 1.031, sea water reg- 

 istering about 1.025. 



