Chemical Science, " 465 



3. Crystallization of Metallic Oxides. — If a solution of nitrate of 

 copper, mingled with very fine charcoal powder, or even deutoxide 

 of copper, be put into a similar tube to that described in the last 

 article, then a plate of copper be introduced and the vessel closed 

 up, iu about fifteen days small red transparent octoedral crystals 

 of protoxide of copper will be formed on the plate of metal. Other 

 metals have been subjected to similar experiments, but probably 

 Iiave not yet remained long enough under action. — -47m. de Chimie, 

 XXXV. 113. 



4. On Bromine^ by M. A. de la Rive. — M. de la Rive has remarked 

 a curious fact respecting the conducting power of fluids for elec- 

 tricity in the habitudes of bromine and water. He found, in the 

 first place, as M. Balard had stated, that pure dry bromine did not 

 conduct the electricity of a voltaic battery, consisting of sixty pairs 

 of plates very strongly charged, a delicate galvanometer being the 

 test : a similar experiment was then made with pure water, the 

 water being contained in a glass capsule, and communicated with 

 the battery and galvanometer by platina wires*, and the deviation of 

 the needle was scarcely sensible. Some other experiments induced 

 M. de la Rive to believe, that water perfectly distilled and put into 

 vessels made of substances absolutely unacted upon, would not 

 conduct any portion of electricity : the purer the water, and the 

 more unchangeable the substance of the vessel, the feebler does the 

 conducting power become, until at last it is insensible. 



A few drops of bromine were then added to the water, which soon 

 acquired a yellow colour, by dissolving a small portion of the sub- 

 stance ; being now included in the voltaic circuit, the galvanometer 

 needle was deviated 70°, and an abundant disengagement of ga^ 

 took place from tlue platina wires. These were oxygen and hydro- 

 gen, in the usual proportion, proving that the water only had been 

 decomposed. 



From these experiments it results, that a body which does not at 

 all conduct voltaic electricity, or at least but very badly, namely, 

 pure watery may be rendered a very good conductor, by its mixture 

 with a few drops of perfectly non-conducting suhstancey namely, bro- 

 mine. M. de la Rive has found the same fact to occur with iodine, 

 and iodine and water; and his father had observed, in a course of 

 experiments made a long time ago on the conducting power of 

 fluids, that diluted sulphuric acid is a better conductor than very 

 much concentrated acid : may not anhydrous sulphuric acid then be 

 a non-conductor like bromine, &c. ? — Annales de Chimiey xxxv. 161. 



b.' Elementary Nature of Bromine. — Iodine colours a solution of 

 starch blue, bromine renders a similar solution orange colour. M. 

 A. de la Rive added a few drops of bromine to a solution of starch 



* Sec, on this point, the statement by M. Becquerel, p. 462, relative to the 

 use of platina wires, when forming a communicating n^edium with fluids. 



