252 Prof. Daniell and Dr. Miller on the 



accounted for upon the hypothesis of the unequal transfer of 

 the oxysulphion and hydrogen of the hydrate to their respect- 

 ive 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 in- 

 soluble in water, we selected it as an extreme test of the fact, 

 and for this purpose prepared some pure tungstate of soda 

 (NaO, WO3) 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 ammonia and nitric acid, it was deci- 

 dedly shown that a portion of the acid had travelled to the 

 zincode cell. 



Neutral chromate qfpotassa (KO, CrOg), which contains an 

 acid forming no definite hydrate with water, furnished a per- 

 fectly analogous result ; and the same thing was observed in 

 the experiments with arsenite qfpotassa. 



{a.g.) The carbonic acid is one of those which seems to 

 have the least affinity for water, but it has been already shown 

 that in the electrolysis of the carbonates of potassa, soda and 

 ammonia, it is given off' as oxy-carbion at the zincode in equi- 

 valent proportions. We now repeated the experiment. The 

 diaphragm cell was charged throughout with carbonate of soda 

 (NaO, CO2) of definite strength, and the gas tube from the 

 zincode cell connected with a drying apparatus, and Liebig's 

 bulbs. The amount of carbonic acid was ascertained by 

 weighing the bulbs, and by careful precipitation of the liquid 

 in the cell by caustic ammonia and chloride of barium. Qy 

 these means it was ascertained that there had been a decided 

 transfer of the acid to the zincode, though in much less pro- 

 portion than that of the sodium to the platinode. From the 

 quantities of acid transferred in these experiments (which 

 quantities however, as they can be considered but approxima- 

 tions to accuracy, we have not thought it necessary to record), 

 it would appear that those acids which form no definite hy- 



