26 
The President gave an account of an aspirator which had 
been contrived for him by Mr. J. B. Dancer, of Cross- 
street, to be used in the analysis of mixed gases, &c. A 
drawing accompanies this description. Two jars graduated 
into parts of a cubic foot or according to pleasure, are mounted 
in brass, and placed mouth to mouth on an axis g, h 9 or the 
white portion enclosed by c , d, e,f. The upper jar is filled 
with water and the taps opened ; then the water flows from 
a to b , the air or gas entering by h, and passing previously 
through any solution that may be used, as at i. The gas 
enters a by the tube k 9 the air in b goes out by c. When a 
is emptied, it is simply turned round by the hand, and b the 
filled bottle stands uppermost. The shaded part of c, d s e 9 f 9 
revolves with the jars, and the openings are so made as to form 
continuations of the openings in the axis g } h. The same 
co nditions exist, no matter which jar is uppermost. This 
apparatus is very convenient in a laboratory, and has an 
advantage over other aspirators in measuring the gas. The 
measurements on the jars are made at a definite pressure of 
water, and this ought of course to be maintained when the 
numbers are read off. The apparatus is certainly very elegant, 
and is an ornamental as well as useful addition to a chemist’s 
work table. It may be called Dancer’s Aspirator, or the 
Swivel Aspirator. 
Dr. Boswell Beid describes one somewhat resembling this, 
but instead of having the swivel movement, it was necessary 
to lift the whole apparatus and to invert it. It was in reality 
two aspirators ; one emptied itself into the other. 
