58 Scientific Intelligence. 
(2.) The second part consists of what amounts to an almost 
theoretically perfect fluid valve, which prevents the air that 
has passed out of the fall-tube from 
returning into it; this is accom- 
plished by merely bending the fall- 
B tube as indicated at V. As for 
the rest, the pump is contrived so 
as to be free from stop-cocks and 
oo grease. és 
By inclining the pump somewhat, the bulb 
" can be exhausted once for all, as matters can 
ad easily be arranged so that when the atmo- 
sphere is allowed to enter the pump, the ex- 
haustion of the bulb remains intact. 
The action of this pump is very rapid, two 
hours or less sufficing to reduce the vacuum 
from 
1 1S 
20,000 £0 90,000,000" the total capacity of 
the pump being 100 cubic centimeters. 
The exhaustion in these experiments was always accom- 
plished by mechanical, not by chemical means; chemical sub- 
stances being introduced solely for the purpose of drying the 
air. In the total absence of all such substances I have ob- 
tained a vacuum as high as 30,000,000" The means of measur- 
ing thése vacua and other details will be given as soon as a 
set of experiments that are being made on the caliber of the 
fall-tube is finished. 
New York, June 10th, 1880. 
SCIENTIFIC INTELLIGENCE. 
I. CHEMISTRY AND PuHysics. 
d be oroform, caused so copious an evolu- 
tion of carbon dioxide that the condensation of the carbonyl bro- 
mide by a freezing mixture was rendered well nigh impossible. 
