240 



SCIENCE 



[N. S. Vol. XXVI. No. 660 



it was found that the amount of water ab- 

 sorbed decreased with increasing tempera- 

 ture. This confirms the results obtained 

 by earlier investigators for the absorption 

 of water vapor as well as for gases in gen- 

 eral. 



Determination of Solid Phases in Four- 

 Component Systems: J. M. Bell, Bu- 

 reau of Soils, Washington. 

 When only one solid phase is present in 

 a four-component system, a modification of 

 the Bancroft method for the determina- 

 tion of the composition of the solid may be 

 employed. By the use of two triangular 

 diagrams in each of which one of the ordi- 

 nates represents the sum of the percentages 

 of two components, the percentage com- 

 position of the solid may be determined 

 graphically. 



Double Sulphates of Ammomum and Cal- 

 cium: J. M. Bell and W. C. Taber, Bu- 

 reau of Soils, Washington. 

 In a recent paper d'Ans has claimed that 

 the formula attributed by us to the double 

 sulphate of lime and ammonium, viz., 

 CaS0,-(NHJ,S0,-2H,0, should have 

 only one molecule of water. It has been 

 found in our later experiments that wash- 

 ing the double salt with the liquids which 

 d'Ans has used, causes a rapid decomposi- 

 tion of the compound, and it has been 

 shown by further experiments that the 

 formula first proposed by us is the correct 

 one. 



Reactions between Copper Sulphate and 

 Lime: J. M. Bell and W. C. Taber, Bu- 

 reau of Soils, Washington. 

 When lime is added in excess to copper 

 sulphate solutions, the solid phases consist 

 of calcium hydroxide, gypsum and blue 

 copper hydroxide, which are thus shown to 

 be the constituents of Bordeaux mixture. 

 When the lime is added in just sufficient 

 quantity to precipitate all the copper and 



the solution is faintly alkaline, there is an 

 olive-green copper hydroxide precipitated. 

 When lime is added in insufficient quan- 

 tity to precipitate all the copper, the pre- 

 cipitate consists of a mixture of gypsum 

 and a basic sulphate of copper. The basic 

 sulphates of copper have been investigated 

 by adding copper oxide to various copper 

 sulphate solutions. It was found that the 

 composition of the solid was variable and 

 was intermediate between the two generally 

 accepted basic sulphates of copper. 



When there is neither acid nor base in 

 excess, the study becomes one of the mutual 

 solubility of copper sulphate and gypsum. 

 The solubility of gypsum passes through a 

 minimum as the concentration of copper 

 sulphate increases. 



The Solubility of Calcium Carbonate in 

 Certain Aqueous Solutions: F. K. Cam- 

 eron and W. 0. Robinson, Bureau of 

 Soils, Washington. 



Calcium carbonate is much more soluble 

 in potassium sulphate solutions than in 

 potassium chloride solutions. In solutions 

 of potassium chloride it passes through a 

 maximum. When the system is saturated 

 with carbon dioxide at atmospheric pres- 

 sure the calcium carbonate is again more 

 soluble in the more dilute potassium sul- 

 phate solutions than in those of potassium 

 chloride, where again it passes through a 

 maximum. In the more concentrated po- 

 tassium sulphate solutions syngenite is 

 formed. 



Copper as Anode in Chloride Solutions: 

 Saul Dushman, University of Toronto. 

 Increasing the concentration of the chlo- 

 ride, or rotating the anode, increases the 

 proportion of cuprous salt formed. The 

 experiments are in agreement with the sup- 

 position that cuprous and cupric salts are 

 formed in such proportions that the solu- 

 tion at the surface of the anode is in equi- 

 librium with metallic copper. 



