410 



SCIENCE. 



[N. S. Vol. XXV. No. 637 



(iron and aluminum phosphate). This 

 material contains a total of 45 to 50 per 

 cent, phosphorus pentoxid, of which 38 to 

 40 per cent, is 'reverted'; also 2.5 to 3.5 

 per cent, ferric oxid and 45 to 50 per cent, 

 aluminum oxid. Liming was of no benefit 

 and acted injuriously in connection with 

 the finely ground unroasted material. The 

 efficiency of the phosphates is influenced 

 by the soil, the other manures, and by the 

 variety of plant in a most marlied degree, 

 hence the danger of drawing conclusions 

 from insufficient data is great. 



The Functions and Agricultural Value of 

 Certain Sodium Salts: H. J. Wheelee, 

 B. L. Hartwell and F. R. Pember. 

 The investigation of this question has 

 been in progi-ess at the Rhode Island Agri- 

 cultural Experiment Station since 1894. 



Plants have been grown in the field dur- 

 ing twelve years by the use of sodium car- 

 bonate and sodium chloride, by the cor- 

 responding potassium salts and by various 

 mixtures of the sodium and potassium 

 salts. Evidence was afforded of a libera- 

 tion of potassium from the soil by the 

 sodium salts. When the supply of potas- 

 sium was limited sodium salts greatly in- 

 creased the yields of the mangel wurzel, 

 turnip, radish and certain other root 

 crops; at the same time the percentage of 

 phosphorus in the dry matter was usually 

 increased. This increase was greater in 

 the case of the carbonates than with the 

 chlorids, however it seemed to be an inci- 

 dental accompaniment of, rather than the 

 cause of, the increased yield. Sodium did 

 not appear to have been of special benefit 

 because of its serving as a better carrier 

 of nitrogen to the plant than potassium, 

 neither was the benefit explainable by 

 virtue of liberating lime or magnesia nor 

 on account of changes in the relation of 

 the two, removed by the plant. 



Sand culture and water culture were 



both resorted to in order to eliminate 

 factors arising in the field. The results 

 thus far secured by water culture show 

 benefit from sodium in the presence of 

 small supplies of potassium, which is not 

 obtained in the same degree when a like 

 osmotic pressure is provided by the em- 

 ployment of salts of calcium. Sodium 

 seems to enable a small supply of potas- 

 sium to produce a larger crop by virtue of 

 performing some part of the functions 

 which potassium may perform if present 

 in sufficient quantities. Sodium used in 

 connection with potassium sometimes pre- 

 vents plants from taking so great an excess 

 of potassium from the soil as they would 

 otherwise remove. 



The Action of Acids on Casein when no 

 Solution takes Place: L. L. Van Slyke 

 and D. D. Van Slyke. 

 When casein is suspended in a solution 

 of acid, the casein takes acid from the 

 solution, the casein remaining solid under 

 proper conditions of dilution of acid, tem- 

 perature, etc. The amount of acid thus 

 taken up by casein varies with the concen- 

 tration of the acid, the temperature, the 

 time of contact and the kind of acid. The 

 phenomena do not indicate simple chemical 

 combination of acid and casein, but corre- 

 spond closely to the conditions described 

 by van Bemmeln as applying to what he 

 calls absorption compounds. 



The Accuracy of Phenolphthalein as an 

 Indicator in Determining the Acidity of 

 Casein: L. L. Van Sly^ke and D. D. 

 Van Slyke. 



In determining the acidity of casein by 

 titration with alkali, different indicators 

 give different results. With phenolphthal- 

 ein higher results are given than with lit- 

 mus or methyl orange. The results with 

 phenolphthalein have been chosen arbi- 

 trarily as being most accurate. Measure- 

 ment of the conductivity of the solution 



