Notice of some recent additions to Chemistry. 71 



method of obtaining oxygon by the action of sulphuric acid on bichro- 

 mate of potash, in organic chemistry, to the preparation of oxygen 

 in large quantities. We have made in this way a largo amount of 

 gas, and have found it exceedingly pure. The proportions recom- 

 mended are 3 parts salt to 4 of acid. We do not think, however, that 

 this method will be much employed, as it is not so economical as that 

 by means of chlorate of potash— a salt now sold in the market at 

 threepence an ounce. 



Another gas, which is of more importance in theory than in prac- 

 tice, is chlorous acid. When sulphuric acid and chlorate of potash 

 made into a paste are distilled, a yellow gas comes over, the formula 

 of which is Cl-04. Its existence may be proved by a simple experi- 

 ment Place some chlorate of potash and phosphorus at the bottom 

 of a test-glass filled with water, and then by means of a sucker add 

 sulphuric acid. The gas is evolved and ignites the phosphorus. 



Millon (L' Institut. 456.) forms this gas by introducing into a large 

 glass flask 1 part tartaric acid, 4 chlorate of potash, 6 nitric acid, and 

 8 water; or, when it is desired to have it perfectly pure, the following 

 mixture is to be used: — arsenious acid 15 parts, chlorate of potash 

 20, nitric acid 60, water 20. The arsenious acid and chlorate of 

 potash are first pulverized, and formed into a paste with a little water. 

 The mixture of nitric acid and water is then poured on them, and 

 gentle heat applied. The materials should be quite pure. 



The fact that calomel could be converted into corrosive sublimate, 

 in the system, was known many years ago. But the exact circum- 

 stances of this transformation were not sufficiently understood. 

 Mialhe, in an elaborate set of experiments on the subject, (Ann. do 

 Chimie, v. 160.) says, the action occurs when calomel is brought in 

 contact with a solution of an alkaline chloride, that the quantity 

 of sublimate formed is in proportion to the amount of alkaline chloride 

 present, and the action increases in proportion to the concentration of 

 the alkaline chloride. His experiments were made with common salt 

 and sal-ammoniac. The action is much increased by the presence of 

 air and dextrine, but is retarded by fat and gum. By simply boiling 

 calomel in distilled water, sublimate is formed. Mialhe extended his 

 observations to all the compounds of mercury, and obtained similar 

 results. He concludes that it is corrosive sublimate which is the 

 active agent in medicine. If this idea should be confirmed, it should 

 lead to the substitution of this form of mercury for all the others. 

 Thesame chemist recommends the hydrous proto-sulphurot of iron as 

 a complete antidote to corrosive sublimate. To prepare it, copperas 

 is to be precipitated with hydrosulphuret of sodium, the precipitate 

 washed and preserved in an air-tight bottle. 



Fritsche of St. Petersburg has communicated to M. Chevreul 

 (L'Institut 460,) a method — an improvement upon that of Licbig — 

 of separating iudigotine, which he considers will serve for testing the 



