Chemistry and Physics. 273 



SCIENTIFIC INTELLIGENCE. 



I. Chemistky and Physics. 



1. The Rusting of Iron in Water. — W. A. Bradbury has 

 made some interesting experiments upon this subject. He found 

 that when bright iron wire was placed in Manchester tap- water 

 it soon became coated with rust and the water gave a blue color 

 with potassium ferrocyanide. When the water was well boiled and 

 the flasks were corked no rust appeared on the wire. When 

 water containing wire was exposed to an enclosed volume of air, 

 one-fifth of the air, corresponding to the oxygen in it, was grad- 

 ually absorbed, and the water showed the presence of ferrous 

 iron in solution. No hydrogen could be collected when the wire 

 was rusted by the ordinary water in a flask containing a delivery 

 tube. However, when carbon dioxide was passed into the water 

 for a short time it did not cause rusting, but iron went into solu- 

 tion, probably according to the reaction, 



Fe + 2H 2 C0 3 = H 2 Fe(C0 3 ) 2 + H 2 , 



bat no hydrogen appeared at first, apparently on account of the 

 oxidation of the nascent hydrogen by the oxygen present. Then 

 after a few days hydrogen began to be liberated and much iron 

 went into solution without any rusting of the wire. The effect 

 of the presence of a large amount of magnesium chloride in the 

 water kept near its boiling point upon iron wire in absence of air 

 was tried. No rust or gas were produced, nor did any iron go 

 into solution. It appears, therefore, that the prevailing opinion 

 that magnesium chloride has a corrosive action upon iron is incor- 

 rect. — Ghem. News, cviii, 307. h. l. w. 



2. The Estimation of Periodates in the Presence of Iodates and 

 Iodides. — It has been found by Miiller and Friedberger that 

 iodates do not react with iodides in sodium bicarbonate solutions, 

 but that periodates are reduced to iodates under these circum- 

 stances with a liberation of iodine corresponding to one-quarter 

 of the oxygen of the periodate. Muller and Wegelik state 

 that it is a long operation to change alkaline carbonates or 

 hydroxides into bicarbonates by means of carbon dioxide in order 

 to carry out the titration, while strong acids cannot be used for 

 the purpose, as they bring about the reaction of the iodate and 

 iodide in the part of the solution where the acid flows in. They 

 have found, however, that boric acid in the presence of borax 

 may be used for the acidification of such solutions, and that the 

 reaction then takes place precisely in the same way as in the 

 presence of bicarbonates. They recommend the titration of the 

 free iodine by means of arsenious acid. The iodate may then be 

 determined by adding potassium iodide, acidifying with sul- 

 phuric acid, adding saturated borax solution until congo-red 



Am. Jour. Sci.— Fourth Series, Vol. XXXVII, No. 219.— March, 1914. 

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