48 Self-sustaining Voltate Battery. 
stance (the conducting plate) is to come equilibrium, by elim- 
inating hydrogen from the electro 
The chemical affinity generates tie electricity by the combi- 
nation of the zinc with the oxygen, and the decomposition of the 
water. Therefore the amount of electricity, and the consequent 
tension which the affinity can generate in a given time, will de- 
pend on the favorable circumstances for chemical action, such as 
the presence of acid to dissolve the oxyd of zinc, which other- 
wise would soon exclude the electrolyte by encrusting the zinc ; 
the presence of water to dissolve the sulphate of zinc; tempera 
ture affecting the solvent capacity of the water, and the reaction 
of the tension against the affinity. 
hen a battery is first charged, all the mepapeiey are prime ; 
from this there is a decline by several ways to the point of no 
action. ‘The decline may result from a alia of the electro- 
lyte or of the conducting plate. The character of the change, 
and the rapidity of decline, will depend wholly on the construc- 
tion of the battery. The construction may be such that the ac- 
tion will wholly cease before even a small portion of the mate- 
rial is consumed. When the zinc plate of a battery is placed in 
such a situation that the generated sulphate of zinc cannot flow 
away, as when the plate is placed at the bottem, horizontally ) of 3% 
the jar, and the arrangements are made such thatthe quantity e 
electricity, and the consequent formation of zie salt, shall ex: 
he rate at which the diffusion of the salt can take plac 
. the zine plate will soon become coated with a crop of crystals. 
As the cessation of action here is visibly due to exclusion of the 
excitant, it follows that in whatever position the zinc plate is” 
placed, just in proportion as the sulphate of zinc excludes the 
excitant, will the capacity of the chemical ey to generate 
the electrical tension decrease. 
Many plans for removing the sulphate of sie from the cell 
have been devised. The most of these have been. based upon 
the idea that the sulphate by its superior gravity would subside 
and saturate the lower parts of the solution. I have tested the 
value of this idea by the following method: Vessels thirty-eight 
inches deep were filled with solutions of the sulphate of various 
degrees of saturation; then, after letting the solutions repose tor 
several days at a uniform temperature, I drew off a portion of 
the liquid at the bottom, and a portion from the depth of three 
inches from the top, and in no case found a differense of density 
to produce more than one degree of Baumé’s hydrometer. But 
I have found that even a saturated solution willal ways be con- 
siderably deficient jusé rs = sy pesscied, that it is not subject 
to agitation. By this tned that a calm solution 
saturated on the top. Ont dhe basis I Gimeno es 
with Mr. J. Green, the well n maker ih gilonephiont AERP: 
