298 



SCIENCE 



[N. S. Vol. XXVII. No. ( 



cylindrical sleeve of this jacket fits a 

 groove of the thermometer tube in such a 

 manner as to prevent the possibility of any 

 water getting to the windings. The wire, 

 which is of german silver of 8/1,000 

 diameter, is put on in layers which are 

 protected from the metallic inner tube and 

 each other by asbestos paper or sheets of 

 mica. 



When properly wound, the tube heats up 

 uniformly, the temperature being readily 

 controlled by means of a small rheostat. 



The Effect of Temperature on the Respira- 

 tion of Apples: Fred W. Moese. 

 The author finds the amount of CO2 ex- 

 haled at 10° and 20° to be respectively 

 about two and four times the amount ex- 

 haled at 0°. This follows the laws of 

 reaction velocity in this respect. 



..Some Notes on Soil Acidity: Fred W. 



Morse and B. E. Curry. 



The authors report the reactions taking 

 place between a number of clays and some 

 common salts. Also some reactions be- 

 tween the organic matter in soils and some 

 common salts. 



The Relation hetiveen the Effects of Acid 

 in Nutrient Solutions, and of Liming: 

 BuET L. Hartwell and F. R. Pember. 

 Field experiments have shown that rye 

 and barley, among the common cereals, are 

 very differently affected by applications of 

 alkaline material. Under conditions re- 

 sulting in no benefit to rye, liming may in- 

 crease 'the yield of barley, 100 to 200 per 

 cent. Comparative water cultures^ were 

 carried on principally with rye and barley 

 seedlings, to see if the addition of acid to 

 the nutrient solution would affect the 

 barley more injuriously than the rye, as 

 might be surmised from the greater sus- 

 ceptibility of the barley to those conditions 

 which are improved by liming. It was 

 'Ann. Rpt. Agr. Expt. Sta., 20, 358-380 (1907). 



shown by repeated experiments that barley 

 was not injured more than rye by the 

 addition of acid. Growth in the case of 

 both cereals was scarcely affected by an 

 initial acidity equal to iV/5,000, even 

 though the nutrient solution was changed 

 every few days during the three to four 

 weeks of the experiments. A depression of 

 about 20 per cent, occurred, however, when 

 the acidity equaled iV/2,500. An increase 

 in the acidity to iV'/l,700 and iV/1,250, 

 decreased the green weight about 40 and 

 60 per cent., respectively. 



The growth was not materially in- 

 fluenced by any degree of alkalinity which 

 was insufficient to cause precipitation from 

 an ordinary nutrient solution. 



The Partial Substitution of Potassium hy 

 Sodium as a Plant Food: B. L. Hart- 

 well, H. J. "Wheeler and F. R. 

 Pember. 



The possibility of an indirect action of 

 sodium in experiments with soil which have 

 been conducted in Rhode Island and else- 

 where, precludes an absolute proof of a 

 direct beneficial action of sodium upon the 

 growth of plants. This fact led to the grow- 

 ing of wheat seedlings in solution^ and 

 to the results which are briefly mentioned 

 here. "When the seedlings were grown in 

 a nutrient solution containing an optimum 

 amount of potassium there was no in- 

 creased growth caused by the addition of 

 sodium. "When, however, the amount of 

 potassium was reduced so that a depression 

 in growth of about thirty per cent, oc- 

 curred within a period of about three 

 weeks, the substitution of an amount of 

 sodium equivalent to the potassium which 

 was withheld, caused about a ten per cent, 

 greater growth than when the deficient 

 amount of potassium, but no sodium, was 

 present. An extra amount of calcium did 

 not cause the increase which was produced 

 •Ann. Ept. Agr. Expt. Sta., 20, 299-357 (1907). 



