Correspondence, 307 
standard of sugar making all through the tropics. The 
West India Islands, Barbadoes, Cuba, Port Rico, St. Croix 
and the Colony of Demarara have produced better sugar 
than usual this year. 
8. The yield from a given quantity of Beet-root is much 
less this year than it was last, that was quite an exceptional 
ear. 
e g. White sugar, fit to eat, cannot be made from Beet-root 
in one operation, in France as cheaply-as brown. Beet-root 
sugar is only consumed in France as loaf sugar, which is 
more expensive to make than brown. 
As an original subscriber, I send you these observations, 
for I am sorry to see anything in your pages likely to mis 
lead the public. 
ze I am Sir, Your Obedient Servant, 
THOMAS D. HILL. © 
Union Club, 121 Piccadilly. 
ON THE DYNAMICAL THEORY OF 
EBLEGERICITY. 
To the Editor of the TECHNOLOGIST. 
S1rR,—I have lately been led, in relation to a new edition 
of my “Elements of Natural Philosophy,” now in the 
_ Press, to reconsider the whole question of electricity, and 
I have become strongly impressed with the reality of the 
dynamic theory, I have hence naturally been induced to 
look about for confirmatory facts; and a strong and (to 
the best of my knowledge and belief) a new fact has 
presented itself to me. It has long been known that if a 
bar of antimony and one of bismuth be connected, and a 
current be transmitted from antimony to bismuth, heat 
will be developed at the point of junction; and, on the 
contrary, if the current pass from bismuth to antimony, 
cold will be produced. Now. it struck me that if in the 
former, as in all cases in which heat is developed in the 
passage of a current, a portion of electric potential is (as I 
believe) converted into ¢hermic potential, or heat, there 
ought in the latter case to be an inductive conversion of 
thermic into electric potential ; and if so, there should be 
a /oss of current in the first instance, and a gazz in the 
second, and such appears to be the fact. 
On duly balancing thermo-element above-mentioned in 
