Improved Laboratory Appliances. 411 
E consists of a vessel considerably deeper than an ordinary 
evaporating-dish ; the one we employed was made of copper 
plated with silver; but the metal dish might be enamelled ; 
or the dish might be made of the same material as ordinary 
evaporating dishes are made of; it is fitted steam-tight into a 
metal steam-jacket, and around it is a rim of sufficient breadth 
for a bell-jar to rest upon. On this rim and also on that of 
the vessel F an india-rubber washer or collar is placed, on 
which the bell-jar is fixed. The end of the suction-pipe 
which terminates a little above the vessel and the end of the 
one in connexion with the bath F we prefer to have closed, 
and to have the tube pierced all round just below the end with 
small holes whose united area is equal to the area of the 
tube. 
On adjusting the bell-jar and setting the air-pump to work 
a vacuum is speedily produced ; and by conveying either the 
exhaust steam, or the steam superheated, or a mixture of the 
exhaust and superheated, into the steam-jacket, we are able 
to obtain different degrees of temperature. In this vessel 
therefore liquids can be speedily concentrated or evaporated 
to dryness, and organic liquids of higher boiling-points than 
water can be speedily and safely dehydrated. We have also 
found it extremely convenient and useful for bringing about 
chemical combinations which are not easily brought about 
under ordinary conditions. 
This evaporating-dish, whatever may be its form, not being 
movable, as it is fixed to the steam-jacket, cannot be used for 
the evaporation of liquids for quantitative purposes; the vessel 
F is therefore designed to carry on these latter operations, as 
well as for drying and dehydrating solid substances. 
F is a steam-tight jacket, the upper surface having dish- 
shaped indentations of different sizes for seating evaporating- 
dishes in. As this vessel is intended to evaporate liquids in 
movable dishes in vacuo with or without steam heat, and also 
for dehydrating solid substances intended for analysis &c, it 
cannot of course be employed for evaporating liquids and 
drying solids at the same time ; and therefore where much 
work has to be done, a similar vessel, but with a flat upper 
surface, would have to be employed for drying the solid bodies. 
It will be seen from the Plate that, by a simple piece of ma- 
chinery, a thermometer is so held that it can be introduced 
into any of the dishes in which evaporation is to take place. 
F is provided, like E, with a rim on which the bell-jar is fixed. 
At the bottom of the steam-jackets E and F a stopcock is 
attached for carrying off the water which is formed by con- 
densation when the steam is first turned on ; the steam, as 
