118 Dr. Hare on the Construction and Applications of the 



upon the apex of the receiver by tlie screw G, and the three 

 cocks H K O being open ; on drawing out the rod the receiver 

 will be proportionally supplied from the bell-glass with the 

 gaseous mixtui'e. The receiver being thus supplied, the cock 

 O of the bell closed, and K and H being open, on pushing the 

 rod home, the gaseous mixture, driving the air before it through 

 the interstices between the gauge-tubes, will in part effect its 

 escape, in part supply in the tubes the place of the air which 

 it has expelled. This process may be repeated two or three 

 times. After the atmospheric air has in this way been re- 

 moved from the apparatus, the cocks between the bell and 

 receiver being open, if the rod be drawn out 200 degrees, 

 200 measures of the mixture, consisting of 100 of each gas, will 

 enter the eudiometer. This being effected, the cock of the 

 bell must be closed. In consequence of the hydrostatic pres- 

 sure to which the gas will have been subjected in the bell, its 

 density within the receiver will be unduly great. Hence the 

 pressure of the screw on the spring must be relaxed until the 

 gauge indicate that the gas within the receiver has, by the 

 escape of a portion of it, become, with respect to pressure, in 

 equilibj-io with the atmosphere. The cock communicating with 

 the gauge is then to be closed, the pressure on the spring re- 

 stored, and an explosion effected. The communication with 

 the gauge is now to be opened. The indicated deficit must be 

 compensated and measured by pushing in the rod, until the 

 columns of water in the interstices of the gauge are on a level. 

 In the next place, close the cock K communicating with the 

 gauge, and open the cocks H L S, which are between the re- 

 ceiver and the receptacle R. Into this receptacle, by forcing 

 the rod home, the gas is to be transferred. Being agitated with 

 the lime-water, it is drawn back into the eudiometer, brought 

 hito equilibrium with the atmosphere, by appealing again to the 

 gauge, and then measured by noticing the number of gradua- 

 tions which the sliding-rod must enter, in order to effect its 

 expulsion. This residual air, and the deficit produced by the 

 explosion being deducted from 200, the remainder will be the 

 quantity of the carbonic acid, and of course of carbonic oxide 

 originally in the mixture; since cai'bonic oxide, in passing to 

 the state of carbonic acid, absorbs half of its bulk of oxygen 

 without any enlargement of volume. 



Analysis qfOlefiant Gas. 

 As a volume of this gas has been ascertained to be equiva- 

 lent to two volumes of carbon and two volumes of hydrogen, 

 it must require three volumes of pure oxygen for its complete 

 combustion, and must leave, after the union, two volumes of 



carbonic 



