A METHOD FOR FILLING BURETS BY VACUUM C.w. EDDY,148 S.
MISSION
ROAD, LOS ANGELES,CALIFORNIA
Glances through any of the chemical periodicals will bring to one's attention a number of methods to deliver liquids to burets. The majority of these methods deliver the liquid to the buret either by gravity or the use of a small pressure bulb worked by hand to force the liquid over into the buret. The proposed method does away with either of these two methods and by the simple opening of a pinch clamp, allows the vacuum to pull the liquid up into the buret. The majority of laboratories nowadays are equipped with vacuum lines and, by an arrangement shown in Figure 1, it is possible by using the simplest of equipment to be found in any stockroom to have a series of burets set up whicb may be filled by theaid of the vacuum. The accompanying diagrammatic drawing illustrates the method of setting up one buret; a series would be just a duplication of one set-up. A is a storage bottle which may be most conveniently set under the titrating table where it is out of sight and not interfering with the work. B is a calcium chloride tube placed in the stopper of the storage bottle when necessary. C is a buret fitted with a two-way stopcock, one outlet of whicb is attached to the tube from the storage bottle. D is the vacuum line connected a t the proper location and a t a convenient height to the T-tube E. F is a small but firm pinch clamp that controls the vacuum. G is another T-tube which is connected to the tube H of small bore, preferably a capillary tube. H i s connected to the buret C, either by a cork or rubber stopper. I is the continuation of the vacuum line to which other buret set-ups similar to the one shown in the diagram may be connected; there being no limit to the number of burets possible to use by this method. In order to fill the buret, the thumb or finger is held over the open outlet of T-tube G and after adjusting the stopcock to the proper position to allow the liquid to flow from the storage bottle to the buret, the pinchcock Fis opened causing the vacuum to act and suck the liquid up into the buret. The buret can easily be dismantled for cleaning purposes by disconnecting the stopper a t the top of the buret and the rubber connection a t the bottom of it. No method of supporting the buret is suggested because almost 964
VOL.8, No. 5
WHY MARKS SHOULD B E RAISED
Y(i5
every one has his own preferred method of attachment, but the author has found that when a large amount of titrating is to be done a special table set aside for the purpose is advisable. The storage bottles may then be placed under the table and a rigid support built on the table or shelf to support the burets.
