AIR WATER SOILS. 523 



entirely larking, and, from the differences in elevation of the same soil forinatinn in 

 different parts of the valley, there are even evidences to disprove the terrace theory 

 of the physiography of the country. Certain it is, however, that the soils were laid 

 down by water, and that in so doing they were sorted out in various grades of fine- 

 ness. Beginning with the present meadows, which are composed of very fine sand 

 and silt, the Podunk region is in a well-defined terrace elevated aljout 20 ft. above 

 the meadows and is composed of one grade coarser material, but still so fine as to be 

 just distinguishable by the eye. 



"The Hartford loam, forming the principal tobacco soil, in extent at any rate, is a 

 grade coarser than this, while the Windsor loam, believed to be the original bottom 

 of the old lake in its shallowest portion, is very coarse sand containing some gravel. 

 These Windsor sands produce the finest wrapper leaf when the season is favorable, 

 but a good crop is secured only one or two years out of live. " 



The reconnoissances of the Sanpete, Cache, and Utah couiities, Utah 

 and the Cache a la Poudre Valley in Colorado show that the presence 

 of injurious amounts of alkali in the soils of those reg-ions is duo to 

 defective drainage, and the introduction of a system of underdrainage 

 by means of tile is recommended. 



In the paper on the theory of solutions as applied to the study of 

 soils there are presented: 



" (1) An outline of the theory of solutions, showing that a solute by virtue of the 

 presence of the solvent behaves as though it were a gas, and that electrolytes present 

 the added phenomena of electrolytic dissociation or ionization. 



"(2) A demonstration that the reactions under investigation are of a reversible 

 type, and in consequence the Mass law is applicable to a study of the equilibria 

 among the solutes. 



" (3) An application of these views, showing how the solubilities of the sulphate 

 and carbonate of lime in nature are increased by the presence of a solute which 

 dissociates but yields no common ion. 



" (4) An announcement of the presence of sodium carbonate in the waters of the 

 Great Salt Lake, Utah, and an explanation of why this fact has isreviously escaped 

 observation, based on the relation which obtains between the ionization products 

 and the solution constant. A similar explanation is offered for the scant amount of 

 lime in the waters of this lake. 



" (5) An examination of the hypothesis of Hilgard as to the role of carbon dioxid 

 in the genesis of alkali, in which it is demonstrated that the phenomena ol)served 

 are more satisfactorily accounted for in terms of the theory of solution, and that the 

 carbon dioxid nuist be regarded as a contril)uting cause, but not a necessary one. 



"(6) An examination of the Hilgard method for the reclamation of black alkali 

 soils, with an explanation of the reactions observed and of the inqiortance of the 

 controlling conditions respecting drainage and the accumulation of carbon dioxid, 

 empirically announced by Hilgard. 



"(7) An examination of the reaction between calcium sulphate and the carbon- 

 ates of ammonium. The use of gypsum for conserving anmionia in manure piles is 

 explained. Some errors, with the reasons therefor, which may accompany the use 

 of ammonium carbonate in analytical operations involving salts of the alkaline earths 

 are pointed out. 



" (8) A. discussion of some analytical prol)lems in a chemical examination of alkali 

 soils. The nature of the problems is made clear. The relative merits of leaching 

 the soils and taking a solution in contact with the soil in preiiaring the sample are 

 discussed, and the advantages in favor of the latter procedure indicated. The neces- 

 sity of making a direct estimation of each constituent is demonstrated. 



