WATER SOILS. 



793 



"In the case of oxalic treatment, the solution was immediately filtered 

 from the insoluble residue; ibe filtrate evaporated to dryness in a plati- 

 num basin, ignited to expel the excess of oxalic acid, and the resulting 

 residue dissolved in hydrochloric acid and treated as usual." 



*' [The results] show that, on the whole, hydrochloric acid exerts a stronger influ- 

 ence on the soil than does oxalic acid, as in both sets of analyses it is noticed tiiat 

 the insoluble residue is, in the case of the hydrochloric acid digestion, about 2 i)er 

 cent lower than is that resulting from the action of oxalic acid. 



"The amount of [lotash (0.73 for the adobe and 0.47 for the sandy soil) dissolved 

 IS identical in the two treatments, while the quantity of lime extracted by hydro- 

 chloric acid is about twice tiiat yielded by the oxalic acid, as is indicated by the 

 ligures 1.15 and 0.62 for the adobe soil, and 0.97 and 0.41 for the sandy. As regards 

 magnesia, there is very little difference. 



"The percentages of iron and alumina are both lower when oxalic acid is used as 

 the solvent. . . . 



"In summing uj) we might say that, except in the case of lime, the results obtained 

 by the action of oxalic acid on soils could receive the same interpretation as that 

 given to tlio.se derived from the hy<lrochl(>ric acid treatment." 



Digestion of soils for analysis, K W. Hilgard and M. E. Jaffa 



{California Sta. Kpt. 18!):) and 1894, pp. (il-63). — In order to ascertain 

 whether the acid commonly used in soil analysis undergoes change of 

 strength in digestion on the steam bath, "50 cc. of hydrochloiic acid, 

 of l.llG sp. gr., obtained by the distillation of the last two thirds of 

 stronger acid under atmospheric pressure, was evaporated on the steam 

 bath to one half its biUk. The same, diluted with 10 percent of w^ater, 

 was similarly treated. Furthermore, the same experiment was made 

 with 2 porcelain beakers ('soil pots') covered with watch glasses, being 

 kept on the steam bath for 5 days, as usually practiced by us in soil 

 digestion. In the latter two cases, the bulk had been reduced to 36 cc, 

 or by somewhat over one fourth of the original volume." 

 The results were as follows: 



Effect of evaporation on the strength of hydrochloric acid of 1.116 specific gravity. 



Desk acid in open beaker 



Desk aciil with 10 per cent water 



Desk acid in coveied porcelain beaker 



Desk acid, with 10 per cent water, in covered porcelain 

 beaker 



strength of acid (anhydrous hydrochloric 

 acid). 



Original. 



Per cent. 

 •>1. 96 

 20. 67 

 22. 96 



20.67 



Evaporated 



to one half 



its bulk. 



Per cent. 

 21. 49 

 21.49 

 21.49 



21.49 



Evaporated 

 to 5 cc. 



Per cent. 



20. 96 



"It will thus be seen tliat under the ordinary conditions of digestion, as heretofore 

 practiced in this laboratory, the changes arising from eva]>oration are absolutely 

 insigniticant, in comparison with tho.se unavoidably resulting from the variable 

 amount of soluble nuitlers in ditlerent soils." 



Analyses of water and remarks on water supply, M. E. Jaffa, M. Curtis, and 

 E. W. 1Iil<;ai;i) (California Sta. Kpt. ISO! and 1894, pp. /.;77-^<5-^).— Analyses of a large 

 number of samples of stream, lake, spring, well, and artesian water are tabulated 

 and discussed. 



