FEBBrTAET 18, 1910] 



SCIENCE 



275 



a double arsenate of ammonium and iron of the 

 formula NHjHjAsOi.FeAsOj. Like the corre- 

 sponding phosphate prepared by the author, the 

 double arsenate readily hydrolyzes when washed 

 with water. It readily dissolves in mineral acids, 

 but is practically insoluble in 50 per cent, acetic 

 acid. Ammonia dissolves it on heating to a deep 

 reddish-brown solution from which 95 per cent, 

 alcohol precipitates a basic double ammonium 

 ferric arsenate. When sodiiun and potassium 

 arsenates were respectively used under the same 

 conditions, precipitates were obtained which from 

 the results of qualitative analysis appear to be 

 the double corresponding alkali arsenate. 



Solubility Relations in Concentrated Solutions: 



Abthue E. Hill. 



An effort has been made to calculate the solu- 

 bility of a salt in solutions of a second electrolyte, 

 throughout a wide range of concentrations. The 

 lack of success of previous investigators has been 

 due to the want of a dilution formula by which 

 the dissociation of one salt might be accurately 

 calculated in the presence of another, under which 

 condition it has long been known that a change of 

 degree of ionization occurs in addition to that 

 brought out by chemical interaction. The formula 

 most often used to express this " neutral salt 

 effect " is that demanded by the isohydric prin- 

 ciple of Arrhenius. It is known, however, that 

 this formula always gives a calculated ionization 

 greater than that experimentally found, and ac- 

 cordingly solubilities calculated by this method 

 are always too low. Arrhenius himself, realizing 

 the inadequateness of his formula, proposed one 

 remedying the defect, but containing three con- 

 stants. The author finds that an adequate for- 

 mula may be written containing only the two 

 constants of the Storch-Bancroft dilution formula 

 for a single electrolyte, and proposes the ex- 

 pression 



Cs = 



<-xc.,XS£#i-7-? 



where Ca and Ck indicate the concentration of 

 the anions and cathions respectively of the simple 

 salt, 2Ca and 2Ck the total concentration of 

 anions and cathions, and Cs the concentration of 

 undissociated salt. 



This dilution law has been used in calculating 

 the solubility of several binary salts in presence 

 of other electrolytes. In cases where the mixture 

 contains no common ion, the calculated results 

 agree with the experimental data within a few 



per cent, even in solutions of high concentration. 

 In the case of mixtures containing a common ion 

 the agreement is less nearly perfect, although in 

 every case it is better than that obtained when 

 the calculations are made according to the iso- 

 hydric principle. 

 Measuring Capillary Ascension in Tuhes of any 



Material: S. Lawrence Bigelow. 



An apparatus was shown with which the capil- 

 lary ascension of any liquid in tubes of any 

 material can be accurately and quickly determined. 



Experimental results were given demonstrating 

 that the ascension of water (and of benzene) was 

 practically the same in tubes of glass, copper, 

 silver and platinum. 



The fact that water will ascend in tubes not 

 wet by it, in tubes of parafBn, bees-wax and cellu- 

 loid, was shown experimentally. The ascension in 

 such tubes is about 70 per cent, of what it would 

 ba in glass tubes. 



The ascensions of a saturated solution of sugar 

 in a tube of sugar, and of a saturated solution of 

 copper sulphate in a tube of copper sulphate, were 

 measured and found to be about two thirds of the 

 ascensions shown by the same solution in plat- 

 inum tubes. Theoretical discussion of these re- 

 sults was deferred to the appearance of the article 

 in the journals. 



The Reaction betioeen Bromic Acid and Hydriodic 

 Acid in Concentrated Hydrochloric Acid Solu- 

 tion: D. L. Randall. 



This paper compares the action of bromic acid 

 and that of iodic acid on hydriodic acid in the 

 presence of strong hydrochloric acid solution, 

 and shows that while the reaction with iodic acid 

 is 



2KI + KIO3 + 6HC1 = 3KC1 + 3KO + 3IC1 

 the reaction with bromic acid is 



SKI + KBrOs + 6HC1 = 4KC1 + 3H,0 



+ IBr + 2ICL 



Test-tube Holder: H. Emeeson Wetheeill. 



Results of three years' studies off and on on the 

 most useful way to bend up a wire into a test- 

 tube holder with a stand, cover glass holder fea- 

 ture, pinch cock, wide utility and practicability, 

 clamp for various positions, opening by one hand. 



Tlie following papers are reported by title. 

 Some Observations on Phosphorescence: W. L. 



Dudley. 

 Solarization without Light: W. D. Banckoft. 

 The Reduction of Zinc by Mercury and the 



E.M.F. of Zinc Amalgams : J. L. Ckenshaw. 



