A. W. Wright—Distillation of Mercury in Vacuo. 481 
prevent any globules of mercury thrown up from the bulb 
entering the portion e. But it might well be somewhat shorter, 
as with proper care in the application of the heat no shocks 
of the mercury in boiling.ever occur. 
Toward the end of. e the glass is narrowed, and, at the angle, 
it passes to a continuation g, which is a straight, vertical tube 
having an interior diameter of about one millimeter. The 
angle is so formed that the globules of mercury running down 
from e fall freely into g without accumulation at any point. 
This part of the apparatus is in fact a Sprengel pump, and the 
mercury as it passes out maintains the exhaustion of the whole 
tube ata very high point. A small tube, / serves to make con- 
nection with the air-pump at the beginning of the operations. 
The tube g, at its lower end, A, is bent upward and a small bulb 
blown upon it, sufficiently large to hold enough mercury to fill 
g itself. Above the bulb the tube is bent into a horizontal 
direction, this part being 30 or 40 millimeters long, and then 
directly downward, forming the outlet for the mercury. The 
total length of g is 90 centimeters. 
cistern, a, serves for the reception of the metal to be 
operated upon. It is a wooden box 150 mm. square, and about 
60 mm. deep. The joints are carefully fitted and the wood 
oiled and then well varnished, being thus rendered quite im- 
pervious. A small well, 80 mm. deep, for the reception of the 
end of the main tube, is made by inserting a thick glass tube 
in the bottom of the box. This arrangement, with the large 
area of the cistern, increases the range of adjustment of the 
The glass tube and cistern are mounted upon a light wooden 
frame, the weight of the former with its contents being chiefly 
large enough to slip through the ring is supported upon the 
latter by a narrow flange at the top. It extends downward 
about 60 mm. and is pierced with a number of holes just be- 
neath the ring. It serves to direct the heated current from the 
burner upon the bulb, as also to protect the flame from move- 
ments of the air, and render it steady in its action. 
The heating apparatus consists of a hollow ring having upon 
the upper surface 12 holes 2°5 mm. in diameter, spaced uni- 
formly in a circle of 25 mm. radius, and concentric with the 
Am. Jour. Seer a Series, Vou. XXII, No, 182.—DrcEemser, 1881 
