lvly
ANALYTICAL EDITION
IS, 1943
467
slight pressure on ges the pellet into idditionsl pressure o the crater. The e electrode holder 1s turned up until ts sufficiently from iolder to be easily
FIGURE2
,ribed is fitted to ,meter with drilled inch, but dimenir construction of d to electrodes of i s is easy to take d with the aid of cleaner. Fragile, by easily be filled wimouc wreaiung. i n e samples may be briquetted by hand pressure or by means of a press .~ operated under known pressures (4).
BaIQuEnmc PRESS,UNASSEMBLED AND ASSEMBLED
I
raised by turning the height adjuster until the top of the electrode presses firmly against the bottom of the steel plate. The powdered sample or sample mixture is placed in the 0.188-inch hole in the top of the mold, using the tap of the mold as a funnel, and is brushed into the mold with a camel's-hair brush. If it is desirable that the sample not touch the upper part of the sidewalls of the mold, a small glass funnel may be used to introduce the sample into the bottom of the mold. The plunger is placed in the mold and pressure is applied t o the plunger head, molding the sample between the bottom of the plunger and the top of the steel plate, I. Thespringraisestheplungerfromthesamplewhenthepressure is released. The mold i8 loosened one turn, the steel plate is removed, and the mold is screwed down until the inside of the mold is in firmcontact with the electrode holder and the
W. T.OLSON AND R. A. SPURR National Advisory Committee for Aeronautics,
Cleveland, Ohio
A
N ALLGLASS pump, which is leakproof and simple in construction, has been found satisfactory for circulating gases or liquids in an experimental apparatus. The pump is a reciprocating piston with two check valves arranged as indicated in Figure 1. Features of construction are the mercury-sealed 5-ml. Pyrex hypodermic syringe that serves as a piston, the vacuum-operated reciprocating motor of the automobile windshield-wiper type, and the mercury-loaded glass check valves. The check valves, which are bulbs 10 mm. in diameter on a 15-mm. length of 4mm. tubing, are ground to form a gastight seat on 8-mm. tubing. A small amount of mercury sealed into each check valve adds weight and ensures mpid and secure seating of the valve. Mercury from the seal around the plunger does not penetrate the piston. The pump delivers gas a t 230 ml. per minute against a head of 1 em. of mercury; the limiting head for gas is 25 em. of mercury. The piston with its mercury seal is gastight. Liquids are delivered at heads limited only by the power of the motor.
State Department of Geology and Mineral Industries for
t
.
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.
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(1) Dietert. H.
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W..J . Optical Soo. Am., 31, 693-6 (1941).
(2) Frenoe.W. D.,Ibid., 32,681 (1942).
(3) H0dge.E. 5.. IND.ENO. C ~ M . , A N A L . E 14,200 D., (1942). (4) Neuhaus, C. J.. J . Optical SOC.Am., 33, 167-74 (1943). ( 5 ) Oahry, H. I., Ballsrd. J. W., and Schrenk, H. H., Ibid.,32, 672-so
(1942).
