PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 565 



should contain one five-hundredth part of sulphuric acid. 100 grammes of 

 this should be shaken with 200 grammes of the amalgam and pure oxj^gen 

 in a flask holding two litres. It is impossible to obtain a full equivalent of 

 peroxide of hydrogen for the sulphate of lead formed, but it will be found 

 that when the shaking lasts ten seconds the amount will be sensibly nearer 

 the theoretical quantity. The peroxide is not found in the water in the 

 presence of coal dust or spongy platinum, owing to their decomposing 

 action, lie has observed lately that there are man}' bodies in the animal 

 and vegetable kingdoms which like platinum, coal and blood corpuscles, 

 have the power of destroj'ing the peroxide of hydrogen. No peroxide is 

 formed in the blood after r(\spiration, nor is it shown in the slow oxidation 

 of organic matters, but it does not follow that none has been formed. 

 These opposite conditions of oxygen play an important part in oxidations 

 of ordinary oxygen at common temperatures ; and particularly in the 

 decomposition of organic matter and the respiration of animals, in com- 

 parison wnth which all other oxidations which take place on the earth are 

 insignificant. 



Thermo-electric Batteries. 



Bunsen has constructed thermo-electric piles of kupferkies and an alloy 

 of two parts of antimony with one of tin, which are ten times more power- 

 ful than the bismuth and antimony series — he also finds that the mineral 

 pyrolusite is superior to bismuth, although inferior to kupferkies. When 

 the pile is to be subjected to high heat copper is substituted for the anti- 

 mony and tin alloy. Ten pairs of the kupferkies-copper elements are 

 equal to a Daniel's battery, having fourteen square centimeters of copper 

 surface. Pyrolusite and platinum have the one-tenth the electromotive 

 force of Daniel's battery. Pyrolusite is chiefly composed of binoxide of 

 manganese. Kupferkies is copper pyrites containing one atom of copper, 

 one of iron^ and four of sulphur. It is easily fused at a high temperature 

 and thus loses much of its power. In a thermo-electric series the native 

 mineral must be used. It is found in Massachusetts, Connecticut, New 

 Hampshire, New York, Virginia, Michigan, and in large quantites in 

 Wisconsin. 



Aluminium. 



Mr.Corbellc's process for extracting this metal from clay consists in 

 first purifying it from foreign matter, then drying it, and treating it with 

 an acid to remove the iron. About six times its weight of sulphuric acid 

 will answer fur this purpose. The clay which has settled is then dried, 

 and mixed wiih twice its weight of prussiate of potash ; the quantity of 

 the latter being increased or diminished according to the amount of silica 

 in the clay. To this mixture, one and a half times the weight of the clay is 

 added of common salt; the mixture is then placed in a crucible and sub- 

 jected to a white heat. After cooling the aluminum will be found in tJje 

 bottom of the crucible. 



Prof. Joy stated that he had tried this process in the laboratory. 



Thallic Alcohols. 



Lamy has described the con)pounds formed by substituting the metal 

 thallium for one atom of hydrogen in wood spirit, common alcohol and 



