ON A PROCESS OF FRACTIONAL CONDENSATION. 129 
n, to leave room for a piece of caoutchouc tube to be drawn over it, and still admit of 
its being inserted in the end of the tube, 2; the flexible tube is drawn on far enough 
to prevent the drops which form on the end of the worm from coming in contact with 
the caoutchouc ; a perfectly tight and convenient flexible joint is now made by press- 
ing the tube, m, over the caoutchouc covering of the end of the worm, 0. The joints 
of the receivers, /, are made in the same manner. 
The vapors which escape condensation in # pass through the receivers, £k and J, to 
the refrigerator B, which contains ice, or a mixture of ice and salt, are there condensed 
and fall back into the receivers, 7; which should stand in a wooden vessel also con- 
taining ice or a freezing mixture. The refrigerator, B, is made with double bottom and 
sides, with an inch space between, which is filled with pulverized charcoal. Being 
tightly covered, a charge of ice and salt will serve for a long day’s operations without 
renewal. In this manner I have been able to collect, in considerable quantity, bodies 
boiling nearly at 0° C., and this from mixtures in which such bodies had been quite 
overlooked by previous investigators. 
It will be observed, on reference to Fig. 2, that the larger distilling apparatus is 
represented as standing in a brick fire-place, with brick-work, cc, a few inches high, 
built up in front; and a sheet-iron apron, pp, folded above. This is for security 
against fire in case of accident, either to the retort or hot bath of oil. As arranged, 
the contents of either or both of these could run out and burn without danger to the — 
operator or the premises, as the brick-work in front would prevent the liquid from 
spreading beyond the fire-place, and the dropping of the sheet-iron apron would cause 
an additional draft, and thus insure the passage of the flames into the chimney. In- 
stead of placing the apparatus in a fire-place, where that is not convenient, equal secu- 
rity against accidents may be attained by the use of my safety heating-lamp,* g, Fig. 1, 
to heat the retort, and safety-furnace, p, containing a Bunsen’s burner, for heating 
the bath. The bottom of this furnace, and also a large part of the sides, is formed of 
wire gauze, such as described for the safety-lamp.t The gauze upon the bottom need 
not be permanently attached to the furnace, but may be simply laid over an opening 
cut in the stool or board on which the furnace is to be placed ; if the furnace be then 
set upon it, taking care that the joint shall be tight around the edge, nothing more will 
be required. A strip of vulcanized caoutchouc, about an eighth of an inch in thick- 
ness, is riveted around the edge of the opening for the door; against this the door 
tightly closes, so that no ignition can take place through the cracks which would 
otherwise remain under the edges of the door. 
* American Journal of Science, 1862 (2), XX XIII. 275. { Loc. cit. 
VOL. IX. 21 
