22 EXPEEIMENT STATION RECORD. 



The average annual rainfall during this period was 1.65 meters (5.4 ft.). 

 The evaporation was approximately one-half of the rainfall. The average 

 amount of nitric nitrogen brought down annually by the rain was 43.35 lbs. 

 per acre, of ammoniacal nitrogen 11.58 lbs. These are much larger amounts 

 than are found in the rainfall of temperate regions and sufficiently large to be 

 of considerable economic importance from the fertilizing standpoint. 



The genesis of dew, W. Godden (Sijmons' Met. Mag., 48 {1913), No. 513, 

 p. 163). — Observations on grass lands are briefly reported from which the 

 general conclusion is drawn that about 69 per cent of a given dew deiwsit is 

 exhaled by the grass, about 25 per cent is precipitated from the atmosphere, 

 and the rest is derived from the soil. 



A sliding rule for the determination of the dew point, absolute and rela- 

 tive humidity, as well as saturation deficiency, A. Korff-Petersen (Ztschr. 

 Hyg. u. InfeUionskranh., 77 {Idllf), No. 1, pp. 111-183, fig. i).— The rule and 

 its method of use are described. 



Combating hail {Bui. Soc. Nat. Agr. France, 14 {1914), No. 2, pp. 130-144, 

 218-238). — An account is given of a discussion of this subject by a number of 

 different persons, in which particular emphasis is laid upon the relation of 

 forests to hailstorms and the possibility of reducing damage from this source 

 by extension of the forest area. 



Electrical protection against hail in Gironde, F. Courty {Vie Agr. et 

 Rurale, 3 {1914), ^o. 12, pp. 313-316, figs. 3).— Positive and negative results ob- 

 tained with "electric niagaras" and similar devices are reviewed without 

 definite conclusions as to their efficacy. 



Surface water supply of St. Lawrence River Basin, 1912, C. C. Covert, 

 A. H. HoRTON, and W. G. Hoyt {U. 8. Geol. Survey, Water-Supply Paper 32/f 

 {1914), pp. 149, pis. 3). — This report presents results of measurements of flow 

 made on streams tributary to Lakes Superior, Michigan, Huron, Erie, and 

 Ontario, and to the St. Lawrence River. 



A summary of mean discharge per square mile shows the almost entire lack 

 of uniformity or agreement between any two streams, " which indicates that the 

 discharge of each stream is a law unto itself, and that all projects dependent 

 upon stream flow, if they are to be developed along the safest and most eco- 

 nomical lines, must be based on records of stream flow collected with great care 

 over a long series of years as near the location of the project under considera- 

 tion as possible." 



SOILS— FERTILIZERS. 



The characterizing of soil according to the molecular composition of the 

 silicates soluble in hydrochloric acid (zeolitic silicates), R. Gans {Internat. 

 Mitt. Bodenk., 3 {1913), No. 6, pp. 529-51 l).^The author summarizes the results 

 of investigations by himself and others as follows: 



The zeolitic silicates show the same general composition and behavior as 

 the artificial aluminum silicates and may like them be considered as chemical 

 compounds. As a result of weathering they do not always occur in the soil 

 in pure form but are frequently mixed with decomposition products. They 

 show the characteristic aluminum silicate molecular composition 3+Mols. Si02 : 

 1 Mol. AI2O3 : 1 Mol. base when protected from weathering by the carbonates of 

 the alkaline earths, i. e., in neutral or alkaline soils. They show a less base 

 content than 1 Mol. base : 1 Mol. AI2O3 when decomposed by acid (carbon dioxid) 

 weathering solutions. The proportions of SiOs to AI2O3 remains 3+ : 1 under 

 such conditions, i. e., in acid soils. They show a less silica content than 3 Mol. 

 SiOj : 1 Mol. AliOa when decomposed by alkaline weathering solutions which 



