Electrolysis of Secondary Compounds. S51 



ascertained that an equivalent quantity of ammonia had been 

 disengaged in the platinode cell, and by precipitation of the 

 chlorine with nitrate of silver, from the liquid thus neutralized, 

 we found that the solution contained the same amount of chlo- 

 rine as before the experiment; the amount of ammonium in 

 combination with it, must, therefore, have remained un- 

 changed : it had received no addition by transfer from the 

 zincode side. The results of the experiment were perfectly 

 clear and decisive. 



{a. d.) In an experiment which was made in the same 

 manner with microcosmic salt (NaO, NH4O, HO, PgOg), the 

 sodium travelled to the platinode, but the whole of the ammo- 

 nium remained in the zincode cell. Here a polybasic acid was 

 used, and yet results similar to those with a monobasic acid 

 obtained. We have still further evidence that the nature of 

 the acid does not appear to be connected with this travelling 

 of the base, from the fact, that when the double tartrate of 



soda and ammonia (t,^tt r\ (^s^'^^yo) ^as electrolysed, 



putting a solution of soda into the platinode cell, the sodium 

 was found to have travelled, but ammonium had refused to 

 do so, as in the other cases already mentioned. 



It was thus ascertained, contrary to the anticipations which 

 we had formed upon its extreme solubility, that ammonium is 

 included in that class of basic compounds which refuse to 

 travel in the voltaic circuit. 



(a. e.) To show that a relation exists between the power of 

 transference in the circuit, and the affinity of the oxides of the 

 metals, for water, the results of three experiments may be 

 taken with salts of potassa, baryta and magnesia. For one 

 equivalent of force as measured by 71 cubic inches of mixed 

 gases from the voltameter, 



14'*2 grains of potassium =^ equivalent, were transferred 

 from sulphate of potassa into sulphuric acid. 



11 '5 grains of barium =^ equivalent, were transferred from 

 nitrate of baryta into a solution of the same salt. 



1*0 grain of magnesium =y2 equivalent, was transferred 

 from sulphate of magnesia into sulphuric acid. 



The experiments are not rigidly comparable together, nor 

 must the quantities be taken as absolute determinations of the 

 amount of each metal which travels in the circuit, but only as 

 indicating a dependence of the transfer upon the attractive 

 power of water or its elements. 



The supposed anomalous transfer of sulphuric acid in the 

 electrolysis of its mixture with water, the investigation of which 

 cost so much labour upon a former occasion*, is now easily 

 * Second Letter, p. 222. 



