JDI.T 7, 1911J 



SCIENCE 



21 



Table IV., where this expectation is realized.) 

 Dominance here has apparently shifted from 

 the white to the yellow character. It would 

 be a matter of great interest to know how 

 the character would behave in later genera- 

 tions and whether the altered dominance may 

 not be due to some independent factor inter- 

 changeable between white and yellow. We 

 get no evidence of such a condition elsewhere 

 in Kellogg's experiments, and the numerical 

 proportions of the yellows and whites in these 

 two broods are a slender basis on which to 

 base such a hypothesis, but these two broods 

 would form a good starting-point in looking 

 for an explanation, if they were followed into 

 later generations. 



Kellogg's experiments seem to the writer to 

 be of value not in respect to their double ma- 

 ting feature, which really has produced noth- 

 ing at variance with the results of single 

 matings, but in their demonstration, in com- 

 mon with Coutagne's experiments, of varying 

 dominance, a matter as yet quite obscure and 

 affording inviting material for further study. 

 It is to be hoped that Professor Kellogg will 

 not fail to put on record the further data 

 mentioned in his paper. 



W. E. Castle 



BussEY Institution, 

 Harvard Universitt, 

 June 7, 1911 



what is white and black alkali? 



The popular distinction between " white " 

 and " black " alkali salts in soils is of consid- 

 erable practical importance, and anything 

 that tends to confuse the farmers' ideas in 

 this respect is regrettable; doubly so when 

 oiScial publications of experiment stations or 

 the Department of Agriculture at Washing- 

 ton lend countenance to such confusion. The 

 cultivation and reclamation of lands affected 

 by alkali salts is comparatively simple when 

 the alkali is " white," but always more risky 

 and difficult when these are "black," and in 

 the latter case are sometimes economically 

 impracticable. 



In a general way, black alkali is sodium 

 carbonate, which after dissolving the humus 



of the soil, leaves black spots on the land 

 where the solution has evaporated ; while white 

 alkali leaves only the white crust of the sul- 

 fate and chloride of sodium. Broadly speak- 

 ing, the sulfate is quite four times less in- 

 jurious to vegetation than the carbonate, 

 while common salt stands in between in this 

 respect. 



Some years ago, it was stated in an official 

 publication, that an observer had " discov- 

 ered" that bicarbonate (hydrocarbonate) of 

 sodium was frequently present in alkali salts; 

 and as laboratory experiments had shown that 

 the bicarbonate was not more injurious than 

 the other two " white " salts, it should, there- 

 fore, be considered as part of the latter. And 

 having been the first to investigate alkali 

 lands in this country, I have been censured 

 for overlooking such obvious facts, giving 

 lands containing the bicarbonate an unde- 

 served bad name. 



Now any one familiar with the occurrence 

 and behavior of the three sodium carbonates 

 — the normal or monocarbonate, the sesqui- 

 carbonate (so-called) or trona, and the hydro- 

 or bicarbonate, can readily understand the 

 reason why I have considered the presence of 

 either of these compounds in the soil equiva- 

 lent to that of the others. The only one of 

 them that occurs as a mineral in nature, and 

 is stable under natural conditions, is the ses- 

 quicarbonate, occurring as trona wherever a 

 solution of either of the other two evaporates 

 spontaneously in the presence of atmospheric 

 air. The monocarbonate absorbs carbonic 

 dioxide from the air whenever exposed, so 

 that when we want to obtain an accurately 

 weighed quantity of the normal carbonate, 

 we must first ignite it. On the other hand, 

 the bicarbonate begins to lose carbon dioxid 

 as soon as exposed to moist air, and upon 

 evaporation its solution leaves a residue of 

 sesquicarbonate, which acts practically as 

 though it contained the normal carbonate, in 

 dissolving humus, causing injury to vegeta- 

 tion, and puddling the soil. 



It is thus obvious that, supposing a soil to 

 contain a solution of bicarbonate only, the 

 latter will, so soon as it is raised to the aur- 



