134 Mr. De Moleyns on the Sustaining Voltaic Battery. 
mity of the two metals, as well as of the preservation of the 
same proximity during action, and which cannot be made 
by any straining, to involve the principle of central forces 
as explained by Prof. Daniell *. 
2ndly. My battery is xof founded upon the principle of 
equal action being produced from a minute as from a large 
surface of the active metal, so long as the inactive metal re- 
mains unchanged}, but upon the contrary principle of pre- 
senting an active surface, at least one-fourth of the inactive, dess 
than that being found to diminish the action. 
3rdly. I do not advocate the use of aczdulated solutions, or 
of amalgamation of the active metal; on the contrary, I sup- 
port the principle of obviating local action, and of preventing 
injurious combinations, by employment of a solution of chlor- 
hydrate of ammonia (par ewxcellenee) in contact with the ac- 
tive metal. 
4thly. I do not assert one of my principles to be that of 
“perfectly preventing the mixture of the liquids on the opposite 
sides of the diaphragm employed {;” on the contrary, I en- 
courage mixture to a certain extent, for it unquestionably 
promotes electrolysis. 
5thly. I did not adopt a diaphragm “in order to prevent a 
deposition of active metal on the conducting surface §,” inas- 
much as I used not one fluid, but two, to which latter case 
that principle does not apply. One of my reasons for using a 
diaphragm was to prevent the too intimate mixture of the 
fluids employed. 
So much for the subordinate principles of construction of 
both combinations. With respect to the general principle of 
the adoption of two fluids, two metals, and a diaphragm, with 
a view to the obtainment of constancy of effect,—that prin- 
ciple having been discovered and promulgated by M. Bec- 
querel in the year 1829, and Porrett’s experiments with dia- 
phragms being previously published,—I believe I was at per- 
fect liberty, in the construction of the sustaining battery, to 
avail myself of any aid I might require from investigations so 
well known, without subjecting myself to the suspicion of 
borrowing from a subsequent invention, an invention of which 
I was utterly ignorant until after my combination was com- 
pleted. I am, Gentlemen, 
Your most obedient Servant, 
London, Dec. 1842. F. W. De Moteyns. 
* See Daniell’s Chemical Philosophy, sect. 701, 705. 
+ Ibid. latter part of sect. 701. 
t See Prof. Daniell’s letter in Philosophical Magazine for April 1842. 
§ See same letter, Philosophical Magazine for April. 
