264 Analysis of Atmospheric Air, by means of Nitric Oxide. 
question descends perpendicularly from the level of the brim of the 
vessel to the bottom; being soldered into a hole in the latter, so 
that the bore being accessible from without, the copper cup at the 
upper end may, when necessary, be touched by a hot iron introduced 
through the pipe. 
The inner vessel of the gasometer consists of a bell glass, B, sus- 
pended by a cord passing over a wooden gallows, with suitable pul- 
leys. The bell has a perforated neck cemented into a brass cap 
furnished with a female screw for receiving a cock. ‘To this cock 
a flexible lead pipe is attached by a gallows screw. Under the cop- 
per cup, a sufficient quantity of phosphorus being placed, and the 
lower vessel adequately supplied with water, the bell glass is sus- 
pended within the lower vessel, as usual with gasometers, and allow- 
ed to descend about a third ofits depth. Meanwhile the cock of the 
tube being open, the air is allowed to escape, so that the liquid with- 
in and without the bell glass may be on a level. The cock being 
in the next place closed, and the phosphorus ignited by means of a 
hot iron, a brilliant combustion ensues. As soon as it declines, the 
iron meanwhile kept in the fire should be again introduced in order 
to sustain the combustion till all the oxygen is absorbed. 
When the air in the bell glass is completely deoxygenated, which 
may be known by the yellow color of the fumes, by depressing the 
bell in the water, the residual nitrogen may be expelled into any re- 
cipient at pleasure, through the flexible pipe attached to the cock 
for that purpose. 
Arr. X.—Large Volumescope, for the Analysis of Atmospheric 
Air, by means of Nitric Oxide; by Rosert Hare, M. D., 
Prof. of Chemistry in the University of Pennsylvania. 
This apparatus illustrates copiously the condensation which ensues 
when nitric oxide gas and atmospheric air are mingled in due pro- 
portion. 
The hollow glass cylinder, which constitutes the maim body of the 
instrument, is four and a half inches in diameter, and thirty in height. 
It is situated over one of the three wells in my pneumatic cistern ; 
being secured between two iron rods well fastened to the shelf below ; 
and terminating above in screws furnished with nuts. By means of 
these screws, and an intervening bar of iron, a brass disk, by which 
