384 p.. of Scientific Societies. 
of a pipe connected with the stop-cock on the boiler, a portion of about 
ten inches in length, near the upper end, being of glass, to produce insu- 
lation, and the remainder of lead, wound into a helix, like the worm of a 
still. This helix was immersed ina bucket of water and snow. When 
the steam was admitted, it became entirely condensed within the pipe, so 
that there was no rush through the air; yet the production of electricity 
was as abundant as with the former arrangements. 
Dr. P. took notice of experiments made, half a century ago, by Volta 
and Saussure, and afterwards by Cavallo, which proved, to their satisfac- 
tion, that electricity was evolved during evaporation “and condensation, 
but which have since been called in question by Pouillet and others, who 
assert that a mere change of state, not accompanied by chemical change, 
never gives rise to electricity. He considered the experiments, now 
made on a large scale, as favoring, if not confirming, the first opinions 
entertained on this subject. 
Dr. P. referred to the satisfactory manner in which these new experi- 
ments seem to explain the sources of electricity in the thunder storm, and 
in volcanic eruptions. — : i 
He then related an experiment in which an insulated iron ball, and 
afterwards a bar of gold, was heated, and a small stream of water po 
on it, so as to be formed into steam at its surface. The first experiments 
seemed to show that the metal was charged with negative electricity, but 
subsequent trials threw doubts upon this conclusion. 
Dr. P. also described experiments made to determine whether electri- 
city was given off during the solidification of liquids,—the substances 
used being melted lead, silver, and gold. In every case, however, the 
gold-leaf electroscope failed to exhibit the presence of any electricity. 
Prof. Henry stated that he had not seen the sparks from steam; but 
that he had obtained feeble electricity from a small ball, partly filled with 
water, and heated by alamp. He agreed with Dr. Patterson in the opin- 
ion, that the source of the electricity was the change of state, but from 
water to. vapor. There was, however, some doubt on the subject ; Pouil- 
let had denied the evolution of electricity from the evaporation of pure 
water. ‘The facts were interesting, particularly on account of the great 
intensity of the electricity. ‘The results, obtained by the philosophers, 
which had been mentioned, indicated electricity of very feeble tension, 
which could only be observed by the most delicate instruments, but here 
