August 14, 1908] 



SCIENCE 



223 



solutions in pyridine. The conclusions readied 

 are that the electrochemical equivalent of silver 

 is independent of the temperature and that Fara- 

 day's law holds for temperatures as low as 

 — 55° C. provided secondary changes taking place 

 at the electrodes are taken into consideration. 

 Replacement of Heavy Metals in Non-aqueous 



Solutions by Metallic Calcium: J. H. Walton, 



Je. (Preliminary Report.) 



A series of experiments have been carried out 

 for the purpose of determining whether or not 

 a strongly metallic substance, such as calcium, 

 is able to replace the heavy metals of salts which 

 are dissolved in non-aqueous solvents. As a 

 typical heavy metal copper was selected, the oleate 

 being the salt used because of its solubility in a 

 large number of solvents. The experiments were 

 carried out by heating the solution at 100° in a 

 sealed tube with a strip of metallic calcium, the 

 surface of which had been scraped until bright. 

 The following solvents were used for the copper 

 oleate: Toluene, xylene, pyridine, carbon tetra- 

 chloride, ethylene bromide, turpentine, paraifine 

 oil, lard oil, carbon bisulphide, aniline, nitro- 

 benzene, amyl acetate. The calcium was tar- 

 nished, but in no case was it coated with copper. 

 Calcium heated with fused copper oleate at 150° 

 for two hours also did not precipitate copper. 

 A number of similar experiments were carried out 

 in which the following alloys of calcium were 

 heated with solutions of copper oleate in the above 

 solvents: Ca-Zn, Ca-Cd, Ca-Pb, Ca-Sn, Ca-Bi, 

 Ca-Sb, Ca-Al, Ca-Hg. In the case of the alloys 

 containing Pb, Zn and Cd, respectively, replace- 

 ment of the copper was observed in pyridine solu- 

 tion; with the other alloys this did not happen. 

 This is in accordance with the observations of 

 Sammis, who found that these metals when 

 heated with certain copper oleate solutions pre- 

 cipitate the copper. In the case of the Ca-Pb 

 alloy it was observed that whereas metallic lead 

 causes the precipitation of Cu only on heating at 

 100° — the Ca-Pb alloy is coated with copper after 

 standing a few minutes at room temperature. 

 The action of the alloys of Ca is being made the 

 subject of further investigation. 



The Absorption of Carbon Dioacid by Certain 

 Bases: F. K. Camebon and W. 0. Robinson. 

 The pressure curves of CO, over various metal 

 hydroxids at 0° C. up to 5 atmospheres pressure 

 were determined. It is shown that solid bicar- 

 bonates of lime, magnesia and ferrous oxide and 

 carbonates of aluminia, ferric oxide and beryllia 

 do not exist under the forenamed conditions. 



The Dry Grading of Powders: E. E. Fbee. 



It is often necessary to grade a powder without 

 wetting it. Bolting cloths are useful for coarser 

 powders, but not for finer. Air elutriation has 

 been used technically to meet this problem and 

 has been used for scientific purposes by Cushman 

 and Hubbard.' This paper suggests an improve- 

 ment of their apparatus, in that the stream of 

 air carrying the suspended powder is introduced 

 into the smallest of a series of percolation jars 

 and passes through them successively in order of 

 increasing size ( instead of the reverse ) . The 

 velocity of the air stream thus decreases from jar 

 to jar and finer and finer powders are deposited 

 in each. The main trouble with this apparatus 

 is due to flocculation of the powder. The finer 

 grains stick to the larger and to the sides of the 

 apparatus and the only fraction which is entirely 

 of the size desired is the last, or finest fraction. 

 The intermediate grades all contain a small 

 amount of finer material. This flocculation is 

 mainly due to water films on the particles and 

 to electrical charges. That due to water is de- 

 creased by drying, but this increases the electrical 

 flocculation. The minimum of flocculation is 

 found when air and powder are almost, but not 

 quite, dry. 

 The Solubility of Basic Copper Carbonate in 



Solutions of Carbon Dioxide: E. E. Fbee. 



The investigations detailed in this paper form 

 part of the studies on the effect of copper salts 

 in irrigating waters, which have been in progress 

 for several years at the Arizona Agricultural 

 Experiment Station. It is shown that the com- 

 pound precipitated from solutions of carbonates 

 and copper salts is of variable composition, but 

 that under the action of carbon dioxide and water 

 for several days it changes to a compound of defi- 

 nite solubility and probably definite composition. 

 The CuO: CO: H2O ratio (molecular) of this com- 

 pound is 1.000: .515: .603. Its solubility in water 

 is greatly increased by the presence of carbon 

 dioxide. With 1,200 parts of carbon dioxide per 

 million about 35 parts of copper per million dis- 

 solve. The solubility in solutions of carbon 

 dioxide is increased by the presence of sodium 

 chloride, sodiiun sulphate and probably calcium 

 sulphate, and is depressed by the presence of 

 sodium or calciiun bicarbonate. 

 The Constitution of Alum Molecules in Solution: 



Chas. L. Pabsons and W. W. Evans. 



Difi'usion experiments with iron, aluminum and 

 chromium alums, both with membranes and agar 



W. Amer. Chem. 80c., 29, 589-597 (1907). 



