ON EVAPORATION AND DISSOCIATION. 
59 
determined by an apparatus modified from that devised by Professor Hofmann. The 
form adopted was simpler than that employed in the research on alcohol. The 
graduated tube A (fig. 1) was completely filled with warm dry distilled mercury ; the 
ether, contained in a small light bulb, was introduced ; the tube was then inverted into a 
temporary mercury-trough B, on the top of a large india-rubber cork C, which closed 
the top of a large glass jar D, full of mercury, and communicating with the reservoir 
Fig. 2. 
by means of a hole through the cork. Through this hole the tube was inserted, and 
pushed down, until its extremity was distant from the bottom of the jar about 
2 centims. A quantity of mercury was then forced out of the jar through the 
tube E, which did not dip so deeply into the mercury as the graduated tube. The 
tube E was then permanently closed. The tube F, which just passed through the 
cork, was connected with a pump and gauge, by means of which the pressure on the 
surface of the mercury could be altered and read. 
