132. D. A. Kreider—Forms of Laboratory Apparatus 
Art. XVI.—Wotes on Convenient Forms of Laboratory 
Apparatus ; by D. ALBERT KREIDER. 
[Contributions from the Kent Chemical Laboratory of Yale College—XLIL ] 
Hot Filter —A convenient and satisfactory hot filter, so 
indispensable in many laboratory processes, may be easily 
improvised whenever steam is available, in the form. which 
appears in fig. 1. It is always ready ; hot ata moment’s notice, 
and without a flame to endanger the fil- 
tration of combustible substances. The 
encasement for the funnel is made by 
removing the bottom of an ordinary flask 
of suitable size in the well known way of 
starting the crack with a scratch of a file 
and then directing it by applying a piece of 
iron heated to redness. Flasks unfit for 
other purposes may be utilized in this way 
and they are more serviceable than large 
glass funnels, because of the tendency of 
the latter to crack if cold when the steam is 
turned on. The neck of the flask is closed 
by a stopper containing perforations for the 
funnel, steam and waste tubes; the latter 
of which, in the absence of a drain pipe, 
may lead to any convenient receptacle. By 
prolonging the conducting tube of the 
steam somewhat above the level at which the condensed water 
is drawn off, higher temperature will be attainable and spatter- 
ing avoided. Escape of steam with the water is prevented by 
the turn in the waste pipe. When steam taps are not accessi- 
ble, steam may be applied from a wash-bottle. 
9. Valve.—In forcing a liquid or gas indifferent to rubber 
from one vessel to another, the ordinary Bunsen valve is 
apt to collapse in such a way as to permit a back flow. I 
have found that a stout glass tube of desirable size, sealed 
at one end and drawn out with an opening in the restric- 
tion, as indicated in figure 2, and a piece of rubber tubing 
containing a smooth slit placed over it, makes a valve in 
which collapse is impossible, and the power of which in- 
creases with the pressure to be overcome. That a valve similar 
in appearance to the one here described has been used, is not 
unknown to me: but the similarity is confined to the appear- 
ance, as will be evident from the following description: The 
restriction should not be greater than is necessary to leave a 
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