452 



SCIENCE 



[N. S. Vol. XLII. No. 1083 



The term chute, while new in this connec- 

 tion, is needed. It may be defined as a 

 " minor plunging synoline on the flank of a 

 much larger anticline or syncline or in a 

 monocline." It causes the isobaths to make a 

 wave in the up-dip direction. 



Saddles 



A saddle is a down fold in the axis of an 

 anticline, or an up fold in the axis of a 

 syncline. This form partakes of the nature 

 of both an anticline and a syncline, as is evi- 

 dent if a model in sheet lead is turned upside 

 down — when we find it is still a saddle, but at 

 right angles to the original one. 



For surfaces involved in recumbent, erect, 

 carinate, isoclinal or fan folds, the present fold 

 terms may be used without modification. 



The greatly increased use of the geologic 

 surface in economic geology has led to the 

 proposal of this specific set of terms, for which 

 the current nomenclature of folds was not 

 adequate. 



EoswELL H. Johnson 



Universitt op Pittsburgh 



the origin of the " niter spots " in cektain 

 western soils 

 In an article entitled " The Origin of the 

 'Niter Spots' in Certain Western Soils," 

 which appeared in the Journal of the Amer- 

 ican Society of Agronomy, Vol. 6, No. 6, Pro- 

 fessors Stewart and Peterson of the Utah 

 Experiment Station state on pages 246, 247 

 and 248 of the publication cited, that. 



The brown color of the "niter spots" is pro- 

 duced by the solvent and decomposing action of 

 the sodium nitrate upon the organic matter of the 

 soil in just the same way that the black color of 

 the black alkali spots is produced by the solvent 

 and decomposing action of the sodium carbonate 

 upon the soil organic matter. . . . 



The color (of the black alkali) is produced by 

 the sodium carbonate, because, being the salt of 

 a weak acid and a strong base, it readily hydro- 

 lyzes, producing sodium hydroxide, or caustic 

 soda, which, as is well known, acts on carbohy- 

 drates, producing a brown color, the intensity of 

 which depends on the concentration of the sodium 

 or potassium hydroxide, thus readily accounting 



for the production of the color of black alkali. 

 Likewise, in the case of sodium or potassium ni- 

 trate, the salt being the result of this union of a 

 strong base and a stronger acid than carbonic 

 acid, does not hydrolyse so easily and as a resuXt 

 there is a smaller amount of sodium or potassium 

 hydroxide present and necessarily the production 

 of a milder color as observed in the brown alkali 

 {niter) spots. The sodium and potassium sul- 

 phate and chloride, being the salts of strong acids 

 and bases, do not hydrolyse, therefore caustic alkali 

 is not produced, and consequently the color is not 

 produced by these alkali salts. 



It will be seen that while the authors state 

 that the alkali sulphates and chlorides are not 

 hydrolyzed at all, being the salts of strong 

 acids and strong bases, they assert that the 

 nitrates are hydrolyzed, though to a less ex- 

 tent than the carbonates, being the salts of a 

 stronger acid than carbonic. The natural in- 

 ference is that the authors regard nitric acid 

 as being a weaker acid than either hydrochloric 

 or sulphuric. 



It has long been recognized that the strength 

 of acids depends upon their degree of ioniza- 

 tion. In the third English edition of Tread- 

 well's " Analytical Chemistry," Vol I., p. 16, we 

 find that in iV/10 solution, nitric and hydro- 

 chloric acids are both ionized in the extent of 

 approximately 90 per cent., while in the third 

 English edition of Ostwald's " Principles of 

 Inorganic Chemistry," p. 248, we find the ex- 

 tent of the ionization of hydrochloric acid in 

 i^/10 solution to be 95 per cent., while that of 

 sulphuric acid is only 57 per cent. It is thus 

 evident that the view, commonly accepted by 

 chemists, that hydrochloric and nitric acids 

 are of approximately equal strength, and that 

 sulphuric acid is considerably less strong, is 

 correct. Since the only salts of the alkalis 

 which are hydrolyzed are their salts with weak 

 acids, it is clear that the sulphates, being salts 

 of a weaker acid than nitric, should be hydro- 

 lyzed to a greater extent than the nitrates. 



On page 247, Table 8, of their article, 

 Stewart and Peterson show that while a 1-per- 

 cent, solution of sodium nitrate dissolved 0.8 

 per cent, of the organic matter of a given soil, 

 a 1-per-cent. solution of sodium sulphate ex- 

 tracted 1.19 per cent, of it, that is to say, 48.75 



