be P. Cooke, Jr., on a new form of Eudiometer. 199 
is nitrogen. Hence, it follows, since chlorine always combines 
with its own volume of hydrogen, that ammonia contains only 
one volume of nitrogen to every three volumes of hydrogen, 
the point to be proved. To complete this series of illustrations 
it only remains to show that in ammonia gas the four volumes 
are condensed to two. For this purpose some dry ammonia gas 
is passed up into the eudiometer tube as in fig. 9. The side 
tube is then replaced as in fig. 7, the mercury level adjusted and 
the position marked with a rubber ring. A stream of electric 
sparks from a Riihmkorff coil is now passed through the gas, so 
ging the connections that the sparks may traverse the 
whole length of the gas column, and the amount of gas should 
small enough to render this possible. The decomposition 
roceeds somewhat slowly, but after sufficient time on readjust- 
ing the level it will be found that the volume of the gas has 
doubled. Besides the experiments described above, there are 
many others, to which these same forms of apparatus are appli- 
cable; but these will suggest themselves to every teacher and it 
18 not therefore necessary to enter into farther details. ee 
Eudiometer—The eudiometer described above, although origi- 
nally contrived for the lecture table has proved to be of still 
greater value in the laboratory, in all processes of gas analysis 
used ina 
Toom of the most variable temperature; for by passing a cur- 
Tent of water, or of steam, as the case may require, through the 
Outer tube the temperature of the eudiometer tube may be easily 
i are passe 
Space between the tubes. Or on the other hand by varying the 
height of the mercury column in the outer tube we may reduce 
he gas to the same volume and measure the difference of ten- 
§10n according to the method of Regnault. This form of eudi- 
Ometer is especially adapted for the admirable methods of gas 
ne devised by Bunsen. The — balls used by - 
- 8€ most readily introduced when the apparatus is ed 
shown in fig. aed the volume of aqueous vapor formed after 
combustion may easily be measured by replacing the current of 
water through the outer tube by a current of free steam. 
