294 



SCIENCE 



[N. S. Vol. XXVII. No. 686 



formulas, 5CuO • 2SO3 • 5H,0 and 4CuO • 

 SO3 • 4H2O, which have the best status in 

 the literature of the basic sulphates of 

 copper. 



When sulphuric acid was added in ex- 

 cess to solutions of copper sulphate, the 

 lines joining the corresponding points rep- 

 resenting the solid and liquid phases pass 

 through points representing the penta-, 

 tri- and mono-hydrates of copper sulphate. 

 At still greater concentrations of acid the 

 anhydrous salt is the stable solid phase. 

 The vapor pressure at which any two of 

 these hydrates exist at 25 degrees, as found 

 by Lescoeur and Others, agrees well with 

 the calculated vapor pressure of the solu- 

 tion at the corresponding invariant points. 



The Action of Nitric and Citric Acid Solu- 



tions upon Ferric Hydroxide: F. K. 



Cameron and W. 0. Robinson. 



At 25° nitric acid dissolves a little more 

 than its own equivalent of ferric oxide 

 with the formation of a definite solid solu- 

 tion of ferric oxide, nitric acid and water. 



From concentrations of nitric acid from 

 30 to 45 per cent. N^Oj the 18-hydrate of 

 the normal salt exists. In a metastable 

 condition it exists to a concentration of 

 55 per cent. NoO^. The stable solid from 

 concentration 45 per cent, to 55 per cent. 

 N2O5 is an acid salt of the formula FCgO,, • 

 4N,0, • 2OH2O. 



Oxalic acid dissolves more than its own 

 equivalent of iron oxide at 25° with the 

 formation of a solid solution of oxalic acid, 

 ferric oxide and water. 

 The Bate of Diffusion of Oxygen through 



Organic Liquids: G. B. Frankfurter 



and G. W. Walker. Reported by title. 

 The Casting of Zinc: W. D. Bancroft. 



Reported by title. 

 Solution in a Dissolved Solid: Charles L. 



Parsons. Reported by title. 

 Reversed Electrolysis: J. W. Turrentine. 



Reported by title. 



Principles Involved in the Construction of 

 College Laboratories: Charles Basker- 

 viLLE. Reported by title. 



The Heat of Ionization and the Reversible 

 Potential of Nickel: E. P. Schoch. Re- 

 ported by title. 



AGRICULTURAL, SANITARY AND FOOD CHEM- 

 ISTRY SECTION 



W. D. Bigelow, Chairman 



Determination of Sulphites in Food Prod- 

 ucts: /Edward GUDEMAN. 

 Paper recommends the use of steam for 

 distillation of sulphurous acid. Acid solu- 

 tions of food products on concentration or 

 during distillation are liable to be decom- 

 posed and sulphur compounds naturally 

 found in the products, distilled over and 

 oxidized and reported as sulphites or sul- 

 phurous acid present. Method of using 

 steam prevents such concentration and de- 

 composition. Results reported on fresh 

 meats, gelatine and eggs. Advantages of 

 method that distillate can be directly ti- 

 trated with iodine solution for sulphurous 

 acid, no danger of bumping or frothing of 

 solutions and no decomposition of products 

 due to concentration of acid solutions. 

 Description of apparatus used for distilla- 

 tion. 



Natural and Modified Starches; An Intro- 

 duction to a Comparative Study of their 

 Physical and Chemical Properties: 

 Chester B. Duryea. 

 The author outlines an effort to decide 

 whether or not starches are essentially 

 homogeneous chemically. Modified starch 

 is defined. Various methods of prepara- 

 tion are given, and also the more con- 

 spicuous phenomena resulting from the 

 "in suspension" and "drying in" proc- 

 esses, which are stated to differ in their 

 effects on the granules because of strati- 

 fication conditions. Opposing elements in 

 old views involving chemical homogeneity 



