CRYSTALLIZATION PRODUCED BY VOLTAIC ACTION. 493 
Hence it follows that the substance subjected to analysis is a subni- 
trate consisting of 
Calcul. result. Result of exper. 
2 atoms of nitric acid ...... ........ Ob) ea. (0:62 
3 atoms of deutoxide of copper ... jai ann IN cao ¥y 
It appears, by this analysis, that the deutoxide of copper is transformed 
into subnitrate of copper. This result enables us to explain the elec- 
tric effects which give birth to the protoxide of copper and its accom- 
panying products. 
The hermetically sealed glass tube contains some deutoxide of cop- 
per, a saturated solution of nitrate of copper, and a plate of copper in 
contact with both. As the deutoxide takes possession of part of the acid 
of the nitrate, it follows that the part of the plate which touches the deut- 
oxide comes into contact with solution of nitrate of copper, which is less 
saturated than that into which the upper extremity is plunged. A cur- 
rent should result from that circumstance, since the plate of copper is 
plunged into two solutions saturated in different degrees. 
The upper extremity is the negative, and the lower extremity the 
positive pole: the former should consequently attract the copper or its 
oxides, and the latter the acid ; and this is precisely what does take place. 
It appears then that there is nothing perplexing in the fact that the prot- 
oxide of copper is deposited on the upper part of the plate. The action 
of this pile must be extremely feeble at first, inasmuch as the deut- 
oxide, especially when it is anhydrous, not acting easily on the acid of 
the nitrate, the difference between those two liquids is very small.. But 
as the nitrate gradually loses its acid, which is not suddenly replaced 
by that of the upper part, it follows that the difference between the 
degree of concentration of the two solutions increases. The chemi- 
cal action of the pile should be in the same ratio. Thus at the close of 
the operation we perceive crystals of copper especially on the upper 
part. As this process is gradual, all the bases from the deutoxide to the 
metal, should be obtained in a crystallized state, those however being 
excepted which are capable of reacting on the nitrate of copper. 
It is proved by experiment that during these different actions no gas 
escapes. For this purpose all that is required is, that instead of closing 
the tube we should cover it with another tube inverted, and likewise 
filled with a solution of nitrate of copper. We find that, whatever may 
be the duration of the experiment, no gas is disengaged in the upper 
part. It appears that the oxygen which results from reducing the deut- 
oxide of the nitrate into protoxide, is carried to the lower part of the 
plate (which is the positive pole), in order to oxidize it, so that it may 
combine with the acid which is also drawn thither by the action of the 
current. But as there is a formation of ammonia, it is likewise neces- 
