136 Scientific Intelligence. 



SCIENTIFIC INTELLIGENCE. 



I. Chemistry and Physics. 



1. Recent investigations o?i hydrogen peroxide. — Our knowl- 

 edge of the chemical nature of this interesting substance was 

 much advanced by the work of Tkaube, chiefly recorded in the 

 u Berichte" of the German Chemical Society from 1882 to 1893. 

 Traube came to the conclusion that hydrogen peroxide cannot 

 possess the same constitution as the peroxides of manganese, lead 

 and silver, because it is not produced, like these, at the anode in 

 electrolysis, but is produced along with hydrogen at the kathode, 

 especially when oxygen is blown against this electrode. He con- 

 sidered it, therefore, not an oxidation-product of water, but a 

 reduction-product of molecular oxygen. This view is also sup- 

 ported by the fact that hydrogen peroxide is never formed by the 

 oxidation of hydrogen by nascent oxygen or other oxidizing 

 agents, while, moreover, it reduces all the powerful oxidizing 

 agents or is destroyed by them. Traube therefore rejected the 

 generally-accepted di-hydroxyl formula, HO.OH, and advanced 

 the view that the substance is a hydride of molecular oxygen, as 

 expressed by the formla H[0:0]H. 



The interest taken in hydrogen peroxide has been considerably 

 increased since Wolffenstein showed that the substance could 

 be purified and concentrated, with but small loss through decompo- 

 sition, by distillation under diminished pressure, (Berichte, 1894, 

 3307). To perform this operation it is necessary that the solu- 

 tion should be free from compounds having an alkaline reaction as 

 well as from every trace of salts of the heavy metals and from 

 solid substances of all kinds. Wolffenstein recommends a simple 

 distillation of the commercial 3 per cent solution under a pres- 

 sure of about 68 mm for the production of small quantities of the 

 pure solution. For larger quantities he advises evaporation at 

 ordinary pressure upon the steam-bath until a concentration 

 of about 20 per cent is reached, then concentration under dimin- 

 ished pressure to 50-55 per cent, after that, extraction with 

 ether (Briihl considers this step dangerous, as will be seen 

 beyond), and finally distillation under diminished pressure. By 

 repeated fractionation he obtained a product which boiled at 84— 

 85° at 65 mm , and which contained 99'1 per cent of the sub- 

 stance. 



Spring (Zeitschr. anorg. Chem., viii, 424) has prepared large 

 quantities of hydrogen peroxide by WolfFenstein's method and 

 has determined some of its physical properties. He found it to 

 have a blue color about half-again as intense as that of water, 

 and concludes that this fact supports Traube's theory concerning 

 the constitution of the compound, because Olszewski having 

 shown that liquid oxygen has a blue color about fifty times a& 

 strong as that of water, he concludes that oxygen retains more of 



