Methods in chemical analysis : originated or developed in the Kent chemical laboratory of Yale university / comp. by Frank Austin Gooch.

  • Frank Austin Gooch
Date:
1912
Catalogue details

Licence: In copyright

Credit: Methods in chemical analysis : originated or developed in the Kent chemical laboratory of Yale university / comp. by Frank Austin Gooch. Source: Wellcome Collection.

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    including the slit, are moistened with glycerin, a nearly perfect vacuum may be retained for several days. The valve thus lubricated with glycerin, when used as a protection in an am- monia wash bottle, will prevent absolutely the access of am- monia to the mouth, and if made according to the directions will act with very little pressure. Placed in the connection between the vacuum flask and water pump ordinarily used in filtration, it has been found a valuable check on the valve of the pump, and when the latter fails this device prevents the back flow of water into the filtrate. In processes which necessitate the use of a partial vacuum, this valve may be employed to hold the vacuum in continual readiness. Force Pump. — By adjusting two of the valves just described to the opposite extremities of a T-tube, with the horizontal limb enlarged or sealed to a larger tube so as to permit the attachment of a large and stout piece of rubber tubing closed at one end, as shown in Fig. 9, a convenient and powerful little force pump is obtained. A stout T-tube of small-bore is cut off short at the two ends at right angles to one another; to one is sealed a tube just large enough to permit the insertion of a valve; to the other, a large tapering tube, slightly lipped so as to hold a piece of rubber tubing firmly and allow of tying the latter if necessary. Of the third end of the tube, a valve like that shown in Fig. 8 is made. The com- pressing rubber should not be of greater length than the hand is able to cover completely, and may be closed with a glass stopper selected to fit tightly. Providing the space through the T-part is kept at a minimum compared with that of the compressing rubber, rapid pumping will be found possible and the power limited only by the strength of the user’s grip. The apparatus may be quickly constructed of materials always at hand. Originally it was made, in about fifteen minutes, of a T-tube to which the necessary enlargements were connected by rubber tubing and the unused space filled by a glass rod. The valves may be inserted directly into the ends of the compressing rubber, but the form shown in the figure is more serviceable. By attaching the lower end to a tapering tube as shown, the pump is easily inserted into a perforated stopper of any size.
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