458 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. The Preparation of Pure Ethyl Alcohol and Some of its 

 Properties. — Since commercial absolute alcohol contains one or 

 two per cent of water, and is usually contaminated also with alde- 

 hyde, L. W. Winkler has worked out a method for purifying it, 

 and has incidentally determined the specific gravity and boiling 

 point of the pure substance. The aldehyde is first removed by 

 adding very finely divided silver oxide and allowing it to act for 

 several days with frequent shaking at ordinary temperature. At 

 the same time, a little caustic alkali is added to combine with 

 the acetic acid produced by the oxidation of the aldehyde. For 

 dehydration, metallic calcium in the form of filings is used. An 

 amount of this metal corresponding to about two per cent of the 

 alcohol is added in the distilling flask, and a gentle heat is 

 applied, so that little alcohol distils over, until the evolution of 

 hydrogen is slight. Distillation then gives a product containing 

 about 99*9 per cent of alcohol, and this when redistilled with 

 about one-half per cent of calcium gives alcohol which is 

 unchanged in specific gravity by further treatment. It is 

 important that a small portion of each distillate coming over at 

 first should be discarded. Specific gravity determinations of 

 alcohol purified in this way gave results practically identical with 

 those of Mendeleeff between 0° and 15°, but between 15° and 30° 

 they were slightly lower than Mendeleeff's. The results gave the 

 following formula based upon weights in vacuo and water at 4° : 



Sp. gr. — 30° = -80629 — -000838* — -0000004^. 



The boiling point was found to be 78*37° at 760 mm and. 77*69° at 

 740 mm , the variation for l mm being *034°. — Berichte, xxxviii, 

 3612. h. l. w. 



2. Double Salts of Mercuric Chloride icith the Alkali Chlor- 

 ides. — In continuation of similar work previously carried out in 

 the Sheffield Laboratory by Professor H. W. Foote, Foote and 

 Levy have studied the sodium-mercuric, potassium-mercuric and 

 rubidium-mercuric chlorides by the solubility' method, which 

 shows very precisely and conveniently all the double salts that 

 are formed at a given temperature. The results show that only 

 one sodium salt, NaCl.HgCl 2 .2H 2 is formed at 25° and at 10°. 

 Three potassium salts, all of which had been described by Bons- 

 dorf, were found : 



2KC1. HgCl 2 . H 2 

 KC1. HgCl 2 . H 2 

 KC1.2HgCl 2 .2H 2 



Five different rubidium compounds were prepared, none of 

 which corresponded to three supposed salts previously described 

 by Godeffroy. They have the following formulae : 



