INDUSTRIAL AND ENGINEERING CHEMISTRY
900
Vol. 14, No. 11
FIGURE 3. CHARGER AND PUMP
checks. The average deviation in the pump rate at 50 ce. per hour is t2.7 cc. Before starting, all air should he expelled from the bellows 80 as to avoid vaporlock. The mommended mw.&ure is to his-
assembly from the charger'(Figure 3). *he pump is then ready fnr
T,CS
modification cons&ts in &&sing the hellom in a cylinder to prevent sidewise movement and dispensing with the two springs (since the pressure within the bellows maintains contact between the bellows and the eccentric). A pump equipped with a */ia-inch outside diameter X 3/.ineh I ~~
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the s&llerbiameter creme betweekthe corrugations. whereas the stainless steel bellows failed at the welded seam.
Acknowledgment The authors acknowledge the able assistance of John Visor-
kis in the development of this pump. AT ATMOSPHERIC PRESSURE. This pump is designed for operation at 15 to 30 pounds per square inch gage. It will operate continuously for months with an occasional oleaning of the ball-
Literature Cited (1) Tropsoh and Mattox, IND.ENQ.Casna.. 26, 1338 (1934).
Determination of Sulfur in Acid-Soluble Sudfides Lam
I. C. FROELICH ,tory, General Electric Co., Cleveland, Ohio
T
HE following method of determining sulfide sulfur is suggested in place of the familiar cadmium sulfide
method. Even fairly large amounts of hydrogen sulfide can be determined conveniently, and no hydrogen sulfide is lost during the titration, as is apt to happen with the cadmium method. While some improvements still should be worked out, the method has given good results. The principle of the method is precipitation of a heavy metal sulEde from an ammoniacal solution and direct back-titre tion of the excess heavy metal. Silver has been found suitahle for the purpose.
movd of hydrogen suffide after Some minutes of boiling, a solution of ahout 5 mams of sodium carbonate in a little water is
acal at the end. When all hydrogen sulfide has been driven over, the delivery tube is disconnected from the sulfur flask and rinsed with little water into a standard 250-ce. flask. The silver solution is cooled to room temperature and likewise transferred Into the standard flask. Rinse waters are used to bring it up to volume. A 100cc. ortion is withdrawn and titrated for excess silver. precise work the solution is just neutralized with nitric or sulfuric acid and sodium bicarbonate and titrated with alkali chloride and fluorescein, or by some other method. For routine
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The sample, containing not more than ahout 0.13 gram of sul-
flask and 2j'cc. 07 50 per cent sdfuuric acid are run in rapidly. The stopcock is closed, leaving a drop of acid as a seal. The flask
iidicator. Filtering isnot necesiary; the end point may be seen sharply as the disappearance of the stronger and yellowish turbidity caused by silver iodide so long as free silver is present. The cyanide solution must be standardized before use in terms of the standard silver solution; its precise nomdity, therefore, is irrelevant and the sulfur content is found in terms of standard silver nitrate.
tilb intb the'flask and heats its contents, cansingthe silver sulfide to eoaylate snd settle out, To ensure completeness of the re-
CALCULATION: 0.1603 X (cc. of 0.1 N AgNOa us(td for io0 cc.) weight of sample
sulfur h s k is extended to reach the bottom of an old 250-co. volu..~. ~~
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