Table II. Total Sulfur by Oxygen Lamp vs. Air Lamp Gas Burning Rate, Total S Found, Cu. Ft./Hour Grains S/lOO Cu. Ft. Air Oxygen Air Oxygen Sample lamp lamp lamp lamp High-B.t.u. oil gas 9 0.7 0.9 3.65 3.83 Aft.er 4 days’ storage in stainless steel cylinder 0 . 7 0.9 3.53 3.69 High-B.t.u. oil gas B 0.7 2.0 23. Ob 23.6 High-B.t.u. oil gas C 0.7 1.0 0.48 0.64 After passage through 1.o 0.00 0.16 CdC12soln.,concd. H2S040 . 7 1.8 4.27 4.26 Synthesis gas 1.5 Natural gas 0.75 1.8 0.01 0.17 ... 2.0 ... -0.05, +0.02 Methane (Matheson)’ ... 2.0 ... -0.03 Hydrogen (electrolytic) a Passed through CdClz soh., Drierite, activated carbon. * Unstable flame.
Table 111. Reproducibility with Gravimetric Finish Grains S/100 Samplea Cu. Ft. High-B.t.u. oil gas A 23.6. 23.7 ~. B 0.8: 0 . 9 0.7, 0 . 8 C D 12.3, 12.0, 12.2 E 29.7, 30.2, 29.6 F 0.3; 0.2‘ Synthesis gas A 1.40, 1.41 B 1.86, 1.86 a Sample volume and rate. 1 cubic foot at 2 cubic feet per hour with oil gas; 2 cubic feet a t 6 cubic feet per hour with synthesis gas.
the range of gases and rates of burning listing in Table I. Results from several analyses made with the oxygen lamp are compared with results from the air lamp in Table I1 (turbidimetric finish). Agreement within 0.2 grain of sulfur per 100 cubic feet, or within 301, in the case of the high-sulfur gas, is shown. Results from the oxygen lamp run slightly higher in most of the tests, but the difference is not substantial in comparison to the reproducibility of the method. If the difference is significant, the error
No. 32, “Non-aerated Burners,” 1944. (2) Am. SOC. Testing Materials, Philadelphia, Pa., “ASTM Standards on Petroleum Products and Lubricants.” D. 27. 1956. Ibid., p.‘ 681. ’ Granatelli, L., ANAL. CHEM.27, 266 (1955). Hakewill, H., Rueck, E. M., Am. Gus Assoc. Proc. 1946, 529-38. Institute of Gas Technology, Research Bull. No. 5 , in preparation.
should be attributed t o the air lamp, as indicated by the substantially zero results obtained with the oxygen lamp on sulfur-free methane and electrolytic hydrogen. The replicate analyses shown in Table I11 indicate the precision found when using the gravimetric finish described by Hakewill and Rueck (6).
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LITERATURE CITED
(1) Am. Gas Assoc. Testing Laboratories, Cleveland, Ohio, Research Bull.
Symposium on Methods for Testing Liquefied Petroleum Gases, St. Louis, Mo., September 1954.
Hydrostatically Operated Electrical Switch Edward W. Toepfer, Human Nutrition Research Division, and Elmer W. Strock, Agricultural Research Center Operations, U. S. Department of Agriculture, Agricultural Research Service, Washington 25, D. C.
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damage to scientific equipment, furnishings, and records, particularly on floors below laboratories flooded as a result of slipped tubing connections or breaks in tubing carrying water to condensers in Soxhlet extractors or similar equipment, can lead to considerable expense. A hydrostatic switch has been devised to shut off both the water supply and electric heating units, if water flow t o the drain fails. ATER
I n usual operation, water from the condenser or from the last in a series of condensers fills tube A constricted a t the bottom and overflows into tube B, and both tubes empty t o the drain. When A is filled with water, hydrostatic pressure causes the mercury in the Utube near the bottom of A to rise in the open arm and thus close the electrical contact on iron alloy or platinum strips. Operating from 115-volt 60cycle line, the circuit when closed opens a solenoid valve in the water line which permits the continuing flow of water. If water fails to reach A, as when tubing is disconnected, the
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ANALYTICAL CHEMISTRY
mercury column shifts toward A , the switch opens, and the break in the circuit automatically shuts off both the water and the electric heaters. T o close the circuit and start the water flowing, tube A requires manual filling with a small amount of water by means of the funnel. The same effect can be obtained by using a manually operated switch in the circuit; however, unless
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this switch is opened after water starts to flow, the safety feature of the device is lost. A regulating valve in the water line in front of the solenoid valve is necessary for adjusting the volume of water flow to the capacity of the condenser or apparatus. I n parallel with the electrical circuit of the solenoid valve are the heaters or, if a heavy load is needed, a relay. The device can be made from materials usually available in most laboratories; a 16 X 150 mm. test tube and 7- and 8-mm. glass tubing, approximately 45 cm. in length, are used for A and B. Constrictions in the mercury U-tube are for smoother operation and glass wool or other material is packed firmly around the insulated contact wires or strips to support them but not to seal the open arm. Any pressure-operated switch can be used with this device, but the U-tube mercury contact switch is readily constructed in the laboratory. A solenoid valve, Sporlan 12-P (Sporlan Valve Co., St. Louis, No.), is satisfactory in the water line, and electrical connections are made with well insulated heavyduty wiring.
