A N A L Y T I C A L EDITION
October 15. 1942
( 8 ) I b i d . , Vol. 11, p. 299, 1929. (9) Ibid.. p. 370. (10) Low,A. H., Chemist-Analyst,30, 18 (1920). (11) Nakai, Z., Bull. Fishery Erpt. Sta. Gow. Gen. Chosen, Ser. D, NO. 3, 1-24 (1933). (12) Popoff, S.,“Quantitative Analysis”, 2nd ed., pp. 156-7, Philadelphia, P. Blakiston’s Son & Co., 1927. (13) Popoff, S.,and Whitman, J. L., J. Am. Chem. Soc., 47, 2259 (1925). (14) Schulek, E., 2. anal. Chem., 68, 387 (1926).
805
(15) Skrabal, A,, Ibid., 64, 107 (1924). (16) Treadwell. F. P., and Hall, W. T.. “Analytical Chemistry”, 7th ed., Vol. 11, p, 563, New York, John Wiley & Sons, 1930. (17) Vosburgh, W. C., J . Am. Chem. SOC.,44, 2120 (1922). (18) Wasserman, C.,and Eskridge, O., Ethyl Corp., unpublished data. (19) Willard, H. H., and Furman, N. H., “Elementary Quantitative Analysis”, 2nd ed., p. 212, New York, D. Van Nostrand Go., 1935. (20) winkler, L. W., Pharm. Zentralhalle. 69, 369 (1928).
Carbon Dioxide Generator J. A. JOHNSTON, Yale University, New Haven, Conn.
A
SOURCE of carbon dioxide gas is frequently desirable in connection with laboratory or research work. Where the gas is used under low pressure, and especially where considerable quantities are desired on short notice, i t is usually cheaper and more convenient t o generate the gas from dry ice than to purchase it in cylinders. The generator shown in Figure 1 has been in successful use for some time in the Chemical Engineering Laboratories at Yale University. This generator is simple in principle, is inexpensive to make, and is free from operational difficulties encountered in previous designs. The body of the generator, A , is made of a 24-gallon Hackney steel drum nith a removable bolt-on cover. The cover is pro-
From Steam
safety Valve c
7 - - - IA
-
E
vided with a 2-inch discharge line, B , a 6-inch handhole, C, and
a stuffing box, E , for the rod supporting the wire basket, D. The discharge line has a pop safety valve set a t 10 pounds per square
inch, and a pressure gage for indicating the pressure in the drum. The handhole cover is grooved for a rubber gasket and is also provided with a small vent line which serves to vent the air trapped in the handhole during filling. This cover is held in place by hinged bolts which fit into slots in a bar running across the top of the cover. This arrangement permits removal or replacement of the cover in a few seconds. An important feature of the generator is the wire basket, D. It is a circular basket made of strap iron covered with 0.25-inch mesh wire cloth. The basket is supported by a steel rod which passes through a stuffing box in the cover. This arrangement permits the basket to be lifted out of the water which fills the lower part of the generator. By adjusting the height of the basket the rate of generation of carbon dioxide can be controlled. The generator is also provided with a steam coil, J , and a valve at the bottom for draining the drum, G . To operate the generator valves F and G are closed, the handhole cover is removed, and the generator is filled about half full of water. Next about 5 pounds of dry ice, broken up into 1 to 1.5-inch lumps, are placed on the basket which has been lifted out of the water. The handhole cover is replaced and the basket is lowered into the water. Generation of carbon dioxide starts immediately. After venting the air from the system through the safety valve and the vent line, valve F is opened to allow the carbon doxide to go into the holder. With this generator i t is Dossible t o generate aboui 50 cubic feet* of gas in 15 to 20 minutes b y the method of operation described. If a higher rate is desired or if the generator is used frequently, i t is necessary to use the steam coils to keep the water lukewarm. The purity of the gas sent to the holder can be controlled b y limiting the amount of air in the generator at the time of filling and b y purging before allowing any gas to go t o the holder.
FIGURE1. GENERATOR FOR CARBON DIOXIDEGas
