Mr. Napier on the Electro-decomposition of Salts. 211 



And the modulus of this expression is the product of the mo- 

 duH of the factors. The above system of types requires some 

 care in writing down, and not only with respect to the combi- 

 nations of the letters, but also their order, it would be vitiated, 

 e.g. by writing 716 instead of 176. A theorem analogous to 

 that which I gave before, for quaternions, is the following : — 

 If A=l+Aj<j.. H-Ayj-r, X = A'i<i.. +Xyiy. It is Immediately 

 shown that the possible part of A~^XA vanishes, and that 

 the coefficients of »j, . . ly are linear functions of .fj , , jt;^. The 

 modulus of the above expression is evidently the modulus of 

 X; hence "we may determine seven linear functions of a^i .. .r^, 

 the sum of whose squares is equal to x^^+ .. +Xy^." The 

 number of arbitrary quantities is however only seven, instead 

 of twenty-one, as it should be. 



XXIX. Observations on the Decomposition qf Metallic Salts 

 hy an Electric Current. By Mr. James Napier*. 



IN the paper I had the honour of reading before the Che- 

 mical Society at the close of the last session upon this 

 subject, I stated my intention of bringing under their notice, 

 in a series of short papers, such phaenomena as seemed inter- 

 esting which might present themselves in my daily avocations. 

 In fulfilling this promise, I must beg leave to remind the So- 

 ciety that they are phagnomena observed during the practical 

 application of electro-metallurgy on the large scale, most of 

 which are apparently at variance with nmny of the prescribed 

 fundamental laws of electro-chemical decomposition, such as 

 that referred to in my last communication, the non-transference 

 of the base of an electrolyte, a subject I intend to discuss in 

 a separate paper at an early opportunity. Some of the ex- 

 periments were made on a small scale with different electro- 

 lytes from those used on the large scale, in order both to 

 verify the results of practice and to ascertain if they were 

 confined to the electrolytes there employed, which are the 

 double cyanides of gold, silver and copper, with potassium. 

 Some of these experiments will be given in detail. 



It is laid down as a fundamental law in electro-decomposi- 

 tion, that there can be no inequality of force in any part of a 

 voltaic current, and that the decompositions dependent upon 

 the current are always in definite proportions, so that the 

 amount of any element or salt radical liberated at one elec- 



* Communicated by the Chemical Society ; having been read January 

 6, 1845. 



