110 CHEMICAL AND PHARMACEUTIC MANIPULATIONS. 
brass soldered copper box 7x9 inches, enveloped by a 
steam-tight jacket, in the door of which are vent holes for 
change of air. The water, or the olive oil which is used if 
the substance requires a heat higher than 212° for its desic- 
cation, is poured through the centre aperture at the top, but 
must not more than half fill the jacket. The lateral open- 
ing is for the reception of a thermometer, which is adjusted 
by means of a perforated cork, for facilitating the regula- 
tion of the temperatures. 
The watch glasses, plates, or capsules in which the sub- 
stances to be dried are placed, rest upon the perforated 
shelves in the interior. 
The thermometer will indicate with precision the tempe- 
rature of the bath, and care must be taken that the latter be 
not allowed to exceed the degree above which the body to 
be dried decomposes. 
When for any reason it is deemed inadvisable to remove 
the filter from the funnel, they may both be dried together 
in a hot air oven, Fig. 9. The apparatus shown in the cut 
is a copper double or single cased cylinder, with a 
movable cover, to facilitate the introduction of the Fig. 9. 
substances to be dried. In its centre is a circular 
aperture for the reception of the thermometer by 
which the heat is regulated. A perforated dia- 
phragm serves as a support for the funnels, watch, 
glasses, capsules or other vessels, and in order to 
promote the evaporation, a current of air through 
the interior is excited by means of the circular 
apertures in its upper and lower circumference. 
These baths are all heated over small furnaces 
or preferably over the gas lamp, a uniform heat 
being maintained by careful management of the flame. 
These extracts are fair specimens of the minute accuracy 
with which our author enters into details. He treats of the 
various operations of the laboratory under distinct heads, 
and enters fully into the most important particulars of each. 
