146
T H E JOURNAL OF INDUSTRIAL A N D ENGINEERING CHEMISTRY
is added, circulation being maintained by the mechanical stirrer. When the oil becomes solid and does not move under an air pressure of 16 in. of water, the temperature is noted and then allowed t o rise, which i t does very slowly. Readings are taken every quarter or half minute, as t h e case may be, the appearance of the oil in the straight part of the tube protruding from the box being taken as the "cold test." TITRATION BENCH By W. A. Vanwinkle 409 E A 6 T BUTTLES S T . , MIDLAND,MICHIGAN
Received November 15, 1920
For making evening titrations' under working conditions approximating very good daylight the titration bench herein described and illustrated has proved very satisfactory.
Titration
I}
1701. 13, N O . 2
5.5 in., is,placed back of the burets, as shown by t h e end view, j - k , in Fig. z . Each buret is held by t w o spring-brass hooks, which turn upon screws, which may be adjusted so as t o hold t h e burets firmly, y e t looselyi'enough t o permit easy raising and lowering during titration. The wooden frame is grooved where it-comes in contact with the burets. Placed directly back of and set snugly up against the entire rear of t h e bench is a portable lighting cornpartment, a n end view of which is shown in Fig. 3. Two 100-watt, nitrogen-filled, blue glass (or daylight) lamps are used, each one being in a line (front view) with a buret.$ A conveniently placed switch t u r n s t h e lamps on and off. This rear compartment consists of a wooden frame, mounted upon a wooden base. The three sides and t h e t o p are of asbestos board. The base is also covered with asbestos board, and t h e
Table
&#a
--
Fig. 1
The base is made of one-inch board, 2 6 . 5 X 11 in., and has inlaid upon its surface, and placed flush with the border, a glass plate 2 5 X I O in., the under side of which has three coats of white (lithopone) paint. Mounted upon this (See heavy lines in Figs. I and 2.) base is a hardwood frame, made of 5,'s X 'I/s in. strips, which holds two triangular ground-glass sides and rectangular ground-glass back in position. One of the triangular plates is indicated b y e, f, and g, in Fig. 2 ; the rectangular plate by a, b , c , and d in Fig. I . These three plates are held securely in position b y having the wooden frame slotted or sawed t o fit the edges of the plates. The vertical edges of the two sides must be butted snugly u p against the back, as shown by h in Fig. 2. T o protect t h e eyes of t h e operator from t h e light a special rectangular screen of ground glass, 2 3 . 2 5 X 1
J . Am. Chern. Soc., 42 (1920), 337.
.-.v..
I
Fig. a
surface of the latter should lie in the same plane as t h a t of the inlaid glass plate lying below the burets; then no interfering shadow will be cast upon this plate. Asbestos board is used t o insure against fire and also because its roughened, dull white surface gives a fairly uniform diffusion of the light. For ventilation a hole should be cut in the rear wall up near the top; also one in each side, near the base. Unless this is done the temperature may mount quite high. All wooden parts are painted a dull white. An electric lamp (not shown) placed on t h e t o p of the lighting compartment and on a line midway between the t w o burets facilitates the reading of the latter. The ground-glass plates are ground upon one side only and t h e smooth surface should be placed toward the burets, otherwise difficulty will be experienced in cleaning t h e plates from spatterings.
