PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 591 



Preparation of Oxygen. 

 A new process has been patented in France for obtaining a sup- 

 ply of oxygen gas from common air by means of highly oxygen- 

 ated compounds, such as chromates and bi-chromates, manganates 

 and per-manganates, which, if deprived of a portion of their oxy- 

 gen by means of steam, have the power of absorbing oxygen again 

 when exposed to a current of dry heated air. The improvement 

 consists in makhig the action continuous by placing in a retort 

 one of the compounds mentioned, and passing into the retort a 

 current of steam. A current of oxygen is carried otf and collected 

 in a gas-holder, while the steam is condensed to water. When 

 oxygen has ceased to be eliminated, a current of dry, heated air 

 is forced into the retort. The compound absorbs a portion of 

 oxygen, and is again ready for the action of steam. Thus by the 

 alternate action of air and steam, the same compound produces 

 oxygen for an unlimited period. The process is said to work 

 with great regularity, and may yet be of considerable importance 

 in metallurgy. 



To Detect Sulphuric Acid in Vinegar. 

 A German journal publishes a neat process, which may be thus 

 briefly stated. Into the vinegar to be tested, put a small quantity 

 of starch, boil the solution down to half its original measure, then 

 drop into it a very minute portion of iodine. If the vinegar is 

 pure, the usual blue tint will be shown; but if it be adulterated 

 with sulphuric acid (elasot), no such coloration will take place, 

 because the action of this acid upon starch converts it into glucose 

 or grape sugar. 



Osmotic Process for Separating Sugar, 

 In France sugar has been lately separated from beet molasses 

 by applying the osmose principle. The membrane used is paper- 

 parchment. Water is passed upward and molasses downward on 

 opposite sides of the membrane. 



Ozone. 



Mr. G. Plante, in a note to the French Academy, states that 

 fifty per cent, more ozone is pi'oduced in the electrolysis of water, 

 when the poles are of lead, than when they are made of platinum. 

 He conjectures the increase is the result of the secondary action of 

 a layer of oxyd on the electrode. 



