388 EECENT PROGRESS IN PHYSICS. 



Kolbe, then sojourning in England, and by Bottger, in Francfort. 

 Kolbe describes the formation of chloride of nitrogen by the electro- 

 lysis of a saturated solution of sal ammoniac in Phil. Mag. XXX, p, 

 336. Bottgen has, as far as I know, never published anything on this 

 subject, but showed the experiment in the laboratory at Giessen. 



The formation of the chloride of nitrogfen is evidently a secondary 

 effect. If we consider the sal ammoniac as chloride of ammonium H^ 

 IS" CI, then, by the decomposition, CI. goes to the positive and H^ N 

 to the negative pole. From H^ N one equivalent of hydrogen is evolved 

 which escapes, leaving Hg N, while the nascent chlorine at the posi- 

 tive pole decomposes the chloride of ammonium, producing chloride 

 of nitrogen and muriatic acid. When to chloride of ammonium H^ 

 N CI 6 equivalents of chlorine are added, 6 CI, 4 H Cl^ (4 equivalents 

 of muriatic acid,) and N CI3 chloride of nitrogen are produced. 



§ 179. Oxijdizing ejects of the oxygen evolved at the positive pole of 

 the battery. — The oxygen evolved by the galvanic current at the posi- 

 tive pole has, in its nascent state, strong oxydizing properties, so that 

 it forms combinations into which the free oxygen, under other circum- 

 stances, would not directly enter. Kolbe has instituted interesting 

 and important experiments on this subject. 



A saturated aqueous solution of chloride of potassium is decomposed 

 between platinum electrodes, by the current from a battery of four 

 Bunsen's cups, in such manner that at first chlorine is evolved at the 

 positive, hydrogen at the negative pole, and free potassa formed, which 

 gives the fluid an alcaline reaction. In proportion as, by the progress- 

 ing decomposition, the fluid is deprived of chloride of potassium the 

 electrolysis acts also upon the water, liberating at the positive pole, be- 

 sides the chlorine, also oxygen, which partly escapes, and partly com- 

 bines chemically with the chlorine, forming at first hypo-chlorous acid, 

 (CI. 0,) and then chloric acid, (CI. O5,) which are found in alcaline 

 solution in combination with the potassa. 



The formation of chlorate of potassa must certainly, under these 

 circumstances, be considered as the result of the action of the chlorine 

 upon the free potassa. But the same process of decomposition also 

 takes place if to the solution of the chloride of potassium even more 

 sulphuric acid is added than corresponds to the equivalent of the 

 potassium, so that no free alkali can occur, with the single difference 

 that in this case hyperchlorate of potassa (KO CI 0;) is formed, 

 which usually crystalizes when the fluid, which becomes hot, has 

 cooled again. 



Finally, also, from pure muriatic acid, especially when a few drops 

 of sulphuric acid are added, a mixture of free chloric and hyperchloric 

 acid is obtained; while, at the same time, free chlorine escapes at the 

 -f- pole and hydrogen at the — pole. Hence it appears that chlorine 

 and oxygen, in the nascent state, combine directly, without the pres- 

 ence of any free alkali, while heretofore the so-called predisposing 

 affinity was considered an essential condition to this combination, (as 

 on passing chlorine through a solution of caustic potassa.) 



A solution of cyanide of potassium is easily oxydized under similar 

 conditions, and cyanate of potassa (KO. Cy 0) is formed. Kolbe 

 could not obtain a higher oxygen compound of cyanogen, corresponding 



