380 Scientific Intelligence. 
one bubble in one, five, ten or fifty seconds, or in as many 
hours. I have compared this instrument with the ordinary 
voltameter and find it much more accurate. By the use of a 
very small insulated electrode and but one aperture, through 
which both the gas and water current must pass, great increase 
of resistance takes place at the moment when the bubble is 
forming; and just before it rises, a sounder magnet included 
within the battery circuit opens, closing again when the bubble 
escapes, thus allowing by means of a Morse register the time of 
recorder, it becomes a measurer not only of the current passing 
at the time, but also of that which has passed through a circuit 
from any source during a given interval. 
Menlo Park, N. J., July 13, 1878. 
SCIENTIFIC INTELLIGENCE, 
I. CHEMISTRY AND PHysICcs. 
oxygen and leave sodium hydrate. In closed vessels, the same 
decomposition takes place more slowly, requiring three months 
for completion. Absolute alcohol preserves it pretty well, if car- 
bon dioxide be excluded. On examining the efflorescence a ve 
* J. Chem. Soc., xxxi, 1, 125, 1877. + Id., xiv, 274, 1862, 
