J. P. Cooke, Jr., on Lecture Experiments. 195 
the brim. This cap, which is easily made from the “stopper 
cord,” should be capable of holding ten or twenty cubic centi- 
meters of the amalgam, and should tightly clasp the tube. More- 
over for this purpose the solid amalgam, above described, should 
» reduced with mercury to the consistency of a thin 
The amalgam is now to be shaken up in the tube for several 
minutes until the decomposition is complete, and then the mouth 
of the tube may be opened under mercury. The liquid will 
tise to supply the place of the chlorine which has been absorbed, 
and on sinking the tube in the mercury trough until the level is 
the same within as without, it will appear that exactly one-half of 
the volume has disappeared. As this, however, would require a 
deep cistern of mercury, and as the interior surface of the tube 
is left in such a very dirty condition as to obscure the result, we 
Prefer to transfer the tube to a jar of water, which, when the 
cap is removed, at once displaces the mercury and washes out 
the interior, without sensibly impairing the accuracy of the ex- 
periment. 
Water—The points to be illustrated in the case of water or 
rather of free steam are all indicated by the equation 
| HH |+[0|=| 4,0 | 
_ There is no more striking experiment in this connection than 
the decomposition of water by sodium, but as made in the usual 
Way the experiment is attended with no little danger. Sodium 
M certain states explodes violently when brought in contact 
With water, and after several accidents of this sort we have sub- 
stituted the solid sodium amalgam above described with | 
results, We place an ounce or more of this amalgam in a 
Lastly we illustrate the fact, that when the clemon enya gn o 
ted in fig. 7. This 
ma known 
