NOTES AND ABSTRACTS IN CHEMISTRY AND PHARMACY. 
599 
melted sealing-wax between its upper edge and the glass; the paper is next 
saturated with oil aud filled with liquid plaster of Paris, and before the mixture 
solidifies, a small wooden handle is placed in the centre. After an hour or so, 
the plaster cone with the adhering paper filter can be withdrawn by means of 
the handle from the funnel, to which it accurately corresponds. The paper on 
the outside of the cone is again covered with oil, and the whole carefully in¬ 
serted into liquid plaster of Paris contained in a small crucible 4 or 5 centims. 
(1§ to 2 in.) in height. After the mixture has solidified, the cone may be easily 
withdrawn ; the adhering paper filter is then detached, and any small pieces of 
paper still remaining removed by gently rubbing with the finger. In this man¬ 
ner a solid cone is obtained accurately fitting into a hollow cone, aud of which 
the angle of inclination perfectly corresponds with that of the glass funnel. 
By the help of these cones the small platinum funnel is made. A piece of 
platinum (Fig. 2 shows the natural size) is cut from foil of such a thickness that 
one square centimetre ( T 4 d in.) weighs about 0154 grm. (2-4 grs.), and from 
the centre a a vertical incision is made by the scissors to the edge cb d. The 
small piece of foil is next rendered pliable by being heated to redness, and is 
placed upon the solid cone in such a manner that its centre a touches the apex 
of the latter; the sides a, b, d are then closely pressed upon the plaster, and the 
remaining portion of the platinum wrapped as equally and as closely as possible 
around the cone. On again heating the foil to redness, pressing it once more 
upon the cone, and inserting the whole into the hollow cone and turning it 
round once or twice under a gentle pressure, the proper shape is completed. 
The platinum funnel, which should not allow of the transmission of light through 
its extreme point, even now possesses such stability that it may be immediately 
employed for any purpose. If desired, it may be made still stronger by sol¬ 
dering down the overlapping portion in one spot only to the upper edge of the 
foil by means of a grain or two of gold and borax ; in general, however, this 
precaution is unnecessary. If the shape has in any degree altered during this 
latter process, it is simply necessary to drop the platinum funnel into the hollow 
cone and then to insert the solid cone, when by one or two turns of the latter 
the proper form may be immediately restored. The platinum funnel is placed 
in the bottom of the glass funnel, the dry paper filter then introduced in the 
ordinary manner, moistened, and freed from all-adhering air-bubbles by pressure 
with the finger. A filter so arranged and in perfect contact with the glass, 
when filled with a liquid, will support the pressure of an entire atmosphere 
without the least danger of breaking ; and the interspace between the folds of 
the platinum-foil is perfectly sufficient to allow of the passage of a continuous 
stream of water. 
In order to be able to produce the additional pressure of an atmosphere, the 
filtered liquid is rectdved in a strong glass flask instead of in beakers.* This 
flask is closed by means of a doubly perforated caoutchouc cork, through one of 
the holes of which the neck of the glass funnel is passed to a depth of from 5 to 
8 centimetres (2 to 3 in.) ; through the other is fitted a narrow tube open at 
both ends, the lower end of which is brought exactly to the level of the lower 
surface of the cork, to the other is adapted the caoutchouc tube connected 
with the pump. The flasks are placed in a metallic or porcelain vessel, in 
the conical contraction of which several strips of cloth are fastened. This 
method of supporting the flask has the advantage that, in one and the same 
vessel, flasks varying in size from 0‘5 to 2‘5 litres stand equally well, aud that, 
by simply laying a cloth over the mouth of the vessel, the consequences of an 
explosion (which through inexperience or carelessness is possible) are rendered 
harmless. 
* These flasks must be somewhat thicker than those ordinarily used, in order to prevent 
the possibility of their giving way under the atmospheric pressure. 
