Chemistry and Physics. 113 
Now let us inquire what amount of pee is abe equivalent | 
of, or is represented by 15 foot-pounds per min 
of No. 18 pure copper wire be coiled into a helix pee spmenneds in 
a pound of water, and if the ends of this wire be connected to 
the poles of one cell of the Grove battery (pint cup size as used. 
in ach ae the Sk veg of the water will begin to rise 
at the in 9} minutes, or 0°105° per minute. Now i 
the peal ' one pound of water be raised one degree (Fah.) 
per minute, this effect will be the scien pgp of 7 772 pounds 
Taised one foot high in space per minute; the heating effect then, 
of our Grove cell upon the water is ‘the equientaals of 0°105 X772 
=381 (call it 80) Sit hace per mi 
is well known that a galvanic battery will perform its max- 
- imum p york araeg the external resistance which it encounters is 
equal to the internal resistance of the battery. Ihave found the 
internal resistance of the pint cup Grove cell to be equal, on the 
pores’ to that of 100 feet of pure copper wire, No. 18 size. 
nce the maximum external effect of the ordinary Grove cell 
sy be set down as the ere of 80 foot-pounds a goes 
ranged, would be capable of he somewhat more than 5,000 
candle lights from a single lam 
. ith sulphuric acid costing 34 cents, nitric acid 10 cents, zine 
: 8 cents, and mercury 50 cents p er pound, the cost of sues 
1,000 Grove cells one hour, while doing their maximu ) 
would be $27.65. This would give for 5,000 candles a eee of 
r candle. 
e cost of gas light per candle per hour would be about one 
mill, if gas costs $3.25 per thousand cubic feet, and if one cubic 
ma pee hour gives the light of three candle 
ith the Smee battery, carefully managed, the cost of 5,000 
candle lights would be about the sam gas. 
Let us now look at the cost of olnecriaiey as developed by the 
Magneto-electric machine. The power expended on the machine 
* is consumed in fric tion, in heating the wires, m: 
a i ich I e 
two-thi 1,300 foot-pound — expended 
the co agnets, etc. and the balance, 800 foot- 
- Seam measured as exte useful effect. Had the external re- 
n larger, a Sonat pro mage of the expended power 
would | have appeared useful e Suppose, however, that 
tilized by this machine 
800 te unds per S sineote sould Ibe ut ; 
7 fel ie Uliana : g purposes. This wonld be i ae 
. ees ae Sot —Gxootn Scan, Yor. XLIV, No, 15%.—Tan; 
ee! 8 
