March 18, 1887. | 



SCIJENCE. 



283 



indeed, much more frequently sought than ob- 

 tained. The language is plain, and the geometri- 

 cal illustrations are numerous and good. The 

 serious faults of the book are sins of omission. 

 We look in vain for the customary chapter on 

 the change of the independent variable, and we 

 find a strange limitation in the treatment of the 

 important subject, 'maxima and minima.' The 

 author here contents himself with the discussion 

 of functions of a single variable. The use of 

 symbolic methods, involving the extension of the 

 mathematical laws for the combination of quantity 

 to the symbols of operation, is necessary in the 

 modern differential calculus. In this work the 

 principle introduced is explained in an excellent 

 manner, but a fuller exemplification of its legiti- 

 mate outgrowth is desirable. More illustrations 

 should be given, especially of the symbolic 

 method of extending Taylor's formula to several 

 variables. The chief strength of the book lies in 

 the chapters relating to the theory of plane curves. 

 In not a few cases we find greater detail and 

 thoroughness than in the corresponding chaptei'S 

 of its predecessors. On the whole, while no de- 

 cided novelty of treatment is shown to those ac- 

 quainted with the best works hitherto published, 

 the production is a creditable, useful treatise, 

 without other faults than those mentioned above. 



Thomas S. Fiske. 



THE ALKALI LANDS OF CALIFORNIA. 



The term ' alkali soil ' is used in California, and 

 the western states generally, to denote any soil 

 which contains an unusual amount of soluble 

 salts, particularly when they render their presence 

 manifest by an efflorescence on the surface. These 

 salts may be simply an excessive amount of the 

 neutral salts found in minute amounts in all soils, 

 or, in those soils more properly designated as 

 alkaline, they may consist in part of carbonate of 

 soda. 



By the natural processes of evaporation at the 

 surface and capillary rise from below, these salts 

 tend to accumulate near or at the surface, thus 

 producing the efflorescence above noted, and also 

 destroying or injuring the crop by their corrosive 

 action on the root-crown. 



In the actually alkaline soils, i.e., in those con- 

 taining carbonate of soda, another injurious effect 

 is also observed. The alkali prevents what is 

 known as the ' flocculation ' of the clay contained 

 in the soil ; that is, it keeps in the finely divided 

 condition seen in * puddled ' clay. Such a soil can 



Alkali lands, irrigation, and drainage in their mutual 

 relations. By E. W. Hilgakd. Sacramento, State. 8°. 



never be brought into proper tilth ; even the most 

 thorough cultivation only succeeds in breaking it 

 up into larger or smaller clods, and leaves it in a 

 condition entirely unsuited for the growth of 

 crops. 



These alkali soils are somewhat abundant in 

 California, notably in the otherwise extremely fer- 

 tile San Joaquin valley ; and the characteristics 

 outlined above have been tolerably familiar for 

 years. It was not, however, until it was dis- 

 covered that the process of irrigation, so essential 

 in the dry climate of that region, was serving to 

 extend the area of these alkali soils, and even de- 

 veloping them where they did not exist before, 

 that the magnitude of the problem which they 

 present was generally appreciated. 



The pamphlet under review is a summary of in- 

 vestigations carried out at different times at the 

 College of agriculture of the University of Cali- 

 fornia, and in connection with the U. S. census 

 of 1880 by Prof. E. W. Hilgard, than whom there 

 is probably no one more eminently qualified to 

 deal with the question scientifically and prac- 

 tically. 



According to Professor Hilgard, the immediate 

 source of the alkali is usually to be found in the 

 soil-water, though it would appear, that, in some 

 cases at least, the lower strata of the soil itself may 

 contain either these salts or compounds which 

 readily yield them by weathering. When reached 

 by digging, the soil-water is not necessarily per- 

 ceptibly salty or alkaline ; but as it evaporates 

 at the surface, and is supplied from below, the 

 soluble salts are concentrated in a very shallow 

 layer at the surface, the solution becoming strong 

 enough to kill crops, or even depositing the solid 

 'alkali.' 



It is thus evident that the most important factor 

 in determining the amount of alkali which ac- 

 cumulates at or near the surface of the soil is the 

 amount of soil water brought up from below by 

 capillary action and evaporated ; and any thing 

 which increases the evaporation will tend to 

 increase the amount of ' alkali ' deposited, and 

 to make its presence perceptible in spots where 

 before it was not present, or present in such 

 minute amounts as to produce no harmful effects. 

 This, irrigation, as ordinarily practised, does. If 

 the irrigation- water is used somewiiat sparingly, 

 so that it all finally evaporates from the surface, 

 two effects follow : first, the greater amount of 

 water passing first downward, and then upward 

 through the upper strata of the soil, tends to ex- 

 haust it more thoroughly of its alkali, concentrat- 

 ing all of it at the surface ; second, by irrigation 

 the soil is moistened to a greater depth than it was 

 by the rainfall only, and thus a greater amount 



