Observations on some Experiments in Electricity. 63 



Hence it appears that the spring months are most favorable to elec- 

 trical operations conducted in an atmosphere not artificially heated ; 

 but that the winter season offers greater facilities than any other for 

 gaining a temporary advantage by elevating the temperature of a 

 close and dry apartment. Professor Hare's remarks, in the last No- 

 of this Journal, on the facility of charging batteries in such an apart- 

 ment, without a connexion with the " common reservoir," is entirely 

 in accordance with my own observations and practice in that particu- 

 lar, nor is it of the least importance whether the battery be insulated 

 or not, or whether its interior surface be charged from the rubber 

 or from the collector, provided the source of the interior charge, be 

 insulated, when the outside of the battery is not. Nor need we be 

 under any apprehension that the more exposed situation of the posi- 

 tive charge, when outside, and its greater facility of passing through 

 the air, will diminish the durability of the charge ; for if the positive 

 charge, when on the inside has a narrow passage by which to get out, 

 so has it when on the outside, a narrow entrance by which to get 

 in ; and the latter course it must take, before the discharge can be 

 effected, — as all will agree, whether they adopt the theory of one fluid 

 or of two. 



In accordance with the foregoing remarks, I have, during the pre- 

 sent month, (July, 1833,) compared the action of a machine, when 

 the dew-point and temperature were 30° apart, with its performance 

 when they were but 5° from each other. In the former case the 

 sparks were nine inches, and in the latter, scarcely one inch. The 

 first experiment was performed on the 19th, when the horizon 

 was partly overcast, (temperature 81° — dew-point 51°,) and the last 

 on the 24th, when the sky was perfectly cloudless ; — temperature 80°, 

 and dew-point 75°. The moisture in a cubic Inch of air on the 19th 

 was .00254757 gr., and on the 24th it was .00537226 gr. 



The following experiments illustrate several of the preceding ob- 

 servations. 



1. July 25th, the temperature in the open air was 79°, and the 

 dew-point 68^°. An apartment which had been closed for two or 

 three days, was found at the temperature of 82°, and with a dew- 

 point at 76°. The machine, (a four feet plate,) was set in motion, 

 having a single pair of rubbers, and collectors on the opposite end 

 of the diameter. The sparks were now one inch and two-tenths 

 long. The quantity of moisture in a cubic inch of this air was 

 .00553634 grains. 



