25G Scientific Intelligence. — Natural Philosophy. 



immersed in the nitrate solution, and which is the positive pole of 

 the pile, becomes covered with copper in the metallic state ; the 

 nitric acid remains in the solution, and the oxygen alone goes to 

 the other end to oxidize the metal. There are then formed on 

 this side crystals of double chloruret. These crystals have been 

 carefully analyzed. The hydrochlorates of ammonia, lime, 

 potash, barytes, &c. yield, with oxichloruret of copper, crystals 

 which belong to the same system of crystallization, and these 

 salts have precisely the same atomic composition. This result 

 affords a verification to the law discovered by Mitscherlich. 

 Other metals were substituted for copper, and the solutions 

 changed. At the first moments of crystallization, the crystal is 

 complete ; but, when the apparatus has wrought for a long 

 time, truncations begin to appear on the angles and edges. To 

 obtain the metallic oxides crystalHzed, another method is adopt- 

 ed. For the protoxide of copper, for example, there is poured 

 into a tube a sohition of nitrate of copper, in the bottom of 

 which is placed deutoxide of copper ; a plate of copper is then 

 immersed in it ; cubical crystals of protoxide of copper gradual- 

 ly form on the part of the plate which does not touch the deu- 

 toxide. The action which determines the formation of this sub- 

 stance has been developed with much detail, as well as the va- 

 rious circumstances which accompany it. The influence of 

 light and the earth's magnetism are sometimes remarked in the 

 above mentioned eff^ects, notwithstanding its feeble intensity. 

 M. Becquerel related an experiment which leaves no doubt on 

 this subject. The author mentioned that the facts exposed in 

 his memoir were the result of two years' experiments. 



!2. Metallic Electricity. — M. Auguste Delarive of Geneva, 

 has constantly observed, that the action produced by the ele- 

 ments of a pile ceases completely when these elements are placed 

 either in a vacuum or in a medium which exercises no chemi- 

 cal action upon them. On the other hand, M. Delarive has 

 repeated with success the experiments of an English chemist, 

 who produced electricity by means of a pile composed solely of 

 zinc. Of the two surfaces of each plate, the one is rough and 

 the other polished. These plates, which, when placed at a dis- 

 tance from one another, only communicate by means of the 

 ambient air, yet develope an appreciable electricity even with- 



