16 
PROFESSOR DANIELL AND DR. MILLER ON THE 
(nh°o}c 8 ^4 Oio), was 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 trie 
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 equi- 
valent 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. 
1T5 grains of barium equivalent, were transferred from nitrate of baryta into 
a solution of the same salt. 
TO grain of magnesium 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 accounted for upon the hypothesis of the unequal transfer of the 
oxysulphion and hydrogen of the hydrate to their respective electrodes. 
We were next induced to seek for some such connexion between the attraction of 
the different acids for water, and their transfer to the zincode. Our experiments had 
already embraced a great variety of acids, differing very much from one another in 
this respect, and in every case the transfer had taken place ; but our attention had 
not yet been directed to the quantitative results. 
( a.f '.) As tungstic acid forms no definite hydrate and is insoluble in water, we 
selected it as an extreme test of the fact, and for this purpose prepared some pure 
tungstate of soda (NaO, WO s ) by fusing together equivalent quantities of the acid and 
carbonate of soda. The product of the operation was dissolved and crystallized. A 
solution was made which contained one-twentieth of its weight of the salt ; it was 
placed in a diaphragm apparatus, and was found to conduct badly. The current was 
transmitted for If hour, when the zincode liquid was found to be distinctly acid, 
owing to the formation of a soluble bitungstate, and the platinode very strongly alka- 
line. Upon precipitating the tungstic acid from both sides, by hydro-sulphuret of 
* Second Letter, p. 222. 
