Aug., 1912
T H E JOZ;R-\-AL OF I N D U S T R I - 4 L A N D ENGIIYEERIA-G C H E A T I I S T R Y .
and lY,stoppering J and connecting .4,Rand D , C , forcing water through I . Fig. I shows a home-made apparatus that gave very satisfactory service until stopcock K was designed to replace pinchcocks r , 2 and 3. Hydrogen may be substituted for air b y connecting air inlet tube in P to a hydrogen generator.
With E-G in position the nodule D should be about 3 cm. below the tubing C. CHEMICALLABORATORY. MERRIMAC CHEMICALCOMPASY, NORTH
TvOBURN, MASS.4CHUSETTS.
NOTE ON PROTECTORS FOR GLASS STOPCOCKS.' BY WALTER0. SNELLING.
DEPARTVEAT O F CHEYISTRP, O H I O AGRICULTURAL EXPERIXENT STATION,
WOOSTER
AUTOMATIC F I L T E R F E E D . B y THOS.A. MITCHELL.
Received hpril 18, 1912.
The accompanying diagram shows a device for automatically supplying solution t o any laboratory filtering medium where a quantity of liquor, or wash water, is required to be filtered. The apparatus is especially serviceable where i t is desired t o filter over night. The main body consists of a pear-shaped funnel of the separatory type, minus the glass stopcock. The neck X is of such size as will take a No. 3 rubber stopper. The outlet I is about 6 cm. long and I cm. inside diameter, being slightly enlarged a t H t o engage the KO, 00 rubber stopper G which is attached, a s shown, to the glass rod E a t F. This glass rod should be of a diameter that 7%-illpass freely through the glass tube B 5 mm. in diameter. A nodule is formed by heating as indicated a t D. The upper portion consists of a No. 3 rubber stopper, A, a glass tube, B, .?cm. long and 5 mm. inside diameter, and a piece of 3//,," pure rubber tubing, C, 15 mm. long. The hole J should be about 4 mm. in diameter and determines the level of the liquor in the filtering apparatus below. I n use, the glass rod E , with stopper G attached, is passed through a t X and the stopper G inserted a t H . The liquor to be filtered is poured in through X, using the protruding glass rod as a guide for the solution, if it be so desired. After the solution has been added, the parts A-B-C, assembled as a unit, are slipped over the upper end of the glass rod and the rubber stopper A made tight a t X . By quickly lifting the glass rod the nodule D will enter the protruding rubber tube C resulting in a n airtight joint a t C and a free passage a t H. The amount of liquor passing through H is regulated by the volume of air which enters through the trap J. The hole J is not absolutely essential, but we find it does away with considerable upm-ard suction of the liquor below, thus assuring a better mashing of the residues in cases where t h a t is the desired result.
613
Received M a y 2, 1912.
Probably every chemist has a t some time or other suffered the inconvenience of having a glass cock drop out and break. I t is not infrequent for such a n accident to result in the loss of the entire apparatus, and a t the best there is involved the loss of the time and expense required in sending the parts back to the maker.
i) II
2
Some months ago Dr Charles E . Munroe called my attention tp a clip or holder which he had devised, and which was being used by him as a n attachment for burets and similar glass apparatus containing stopcocks. The device is simple, easily made, and admirabll; answers its purpose. It consists of a piece of sheet hard-rubber, so shaped as to encircle some glass part of the apparatus, while a small 2-tined fork passes around the thinnest part of the movable portion of the cock, holding it so securely as to prevent it from dropping out, no matter in what position the apparatus is held, while a t the same time allowing perfect freedom of motion of the stopcock, and also enabling the cock to be removed when desired. I n Fig. I is shown the blank, as cut from sheet rubber, for one form of the Munroe holder, and Fig. 2 shows this form attached to a buret. Ordinary hard rubber sheets of about 3 / / 6 1 ' f thickness is the most convenient material from which t o make the blanks. After the blank has been cut i t is placed in boiling water for a few minutes to soften, when i t may be bent in any desired form, and upon becoming cold will retain whatever form has been thus given it. Fig. 3 represents another form of the Munroe clip, and one which has also been found to give very satisfactory results. This form is placed permanently upon the apparatus by the blank being bent into Published by permission of the Director of the U. S. Bureau of Mines.
