5 64
INDUSTRIAL AND ENGINEERING CHEMISTRY
In general, results obtained here have been in fair accord with those reported by other workers upon sardine and tuna oil. The variation of antirachitic potencies of the sardine oils tested is not great. Only one of the oils proved as good a source of this factor as the medicinal cod liver oil, although all exceeded the requirement of the American Drug Manufacturers’ Association for cod liver oil. Two samples of refined tuna oil were slightly inferior to three samples of raw sardine oil, and two were the equal of one sardine oil and the medicinal cod liver oil. The greater variability of vitamin D in the refined tuna oils may be due to differences in refining processes, which would be one factor limiting the ultimate vitamin D potency of refined tuna oil. It is suggested that refined tuna oil, since
Vol. 25, No. 5
it is produced from edible portions of the fish and possesses a light yellow color and a mild fish flavor, may be acceptable as a source of vitamin D in human therapeutics. LITERATURE CITED (1) Amundson, Allardyce, and Biely, Sci. Agr. (Canada), 9, 594 (1929). (2) Bills, J. BioZ. Chem., 72, 751 (1927). (3) Bills and McDonald, Ibid., 68, 821 (1926). (4) Brocklesby and Denstedt, Can. Chem. Met., 14, 29 (1930). (5) Holmes, J. Am. Pharm. Assoc., 20, 588 (1931). (6) Nelson and Manning, IND. ENQ.CHEM..22, 1361 (1930). RECEIVED November 8, 1932. Presented before the Division of Medicinal Chemistry a t the 84th Meeting of the American Chemical Society, Denver, Colo., August 22 to 26, 1932.
Effect of Particle Size on Capacity of Zeolites PAULBIRD, FRANKCOLBURN,AND FRANKSMITH,Iowa State College, Ames, Iowa
I
N ORDER to make comparative tests for the matersoftening capacity of zeolites, it is essential that the size of the particles tested be stated. Fine materials have a greater area per unit of volume than coarse materials. As the action of zeolites is a function of the availabIe surface, it is apparent that comparable results can be obtained only
than the mesh size. The values given for the average length of side were taken from data prepared by the W. S. Tyler Company (2). The capacity of the zeolites is stated in terms of grams of calcium carbonate equivalent of hardness removed from water per liter of zeolite. Each point is the average of ten runs, and is calculated from results originally
from zeolites of the same size. SCREENSIZE The most common method of expressing particle size is by designating the sifting screen that will just pass the material, and that screen that will retain the material under investigation. Thus to state that a zeolite is of 30- to 40mesh size means that the zeolite will just pass through a screen having 30 openings per square inch (per 6.5 sq. cm.) and be retained on a screen having 40 openings per square inch. Even the statement of the mesh size is not sufficient, as there are several types of screens in use, and a screen of one series having 30 openings per square inch may not possess openings of the same size as a screen of another series having 30 openings per square inch. This is due to the fact that wires of different size may be used in making these two series of screens. Thus, it is also important to state the name of the series of screens used. I n this laboratory the Tyler Standard screen scale sieves are used (2).
EXPERIMENTAL PROCEDURE Four samples of different zeolites were carefully screened on Tyler screens, washed free of phenolphthalein alkalinity, and tested in miniature water softeners for capacity. The sizes of the screens used were the 8, 10, 14, 20, 28, 35, 48, and 65-mesh screens, which had openings of 2.362, 1.651, 1.168, 0.833, 0.589, 0.417, 0.295, and 0.208 mm., respectively. The method of testing has been described (1). The steps required are backwashing to loosen the bed, salting by allowing brine to flow downward through the bed, washing to remove the salt, and softening, During the softening period the hard water was passed downward through the bed at such a rate that 4 hours were required to exhaust the zeolite. A run was considered to be complete when the effluent water showed 17 p. p. m. of hardness. The water contained 376 p. p. m. of hardness. I n order to plot the values obtained (Figure 1) the average length of side, or dimension, of the particles was used rather
10
M
a4
1
LENGTH OF SIDE- mm. 0.6 0.8 1.0 L2
I
/.e
L6
A8
20
&?
FIGURE 1. RELATION BETWEEN CAPACITY AND PARTICLE SIZE
expressed as grains of calcium carbonate per cubic foot, using 2.31 grams per liter as equal to 1000 grams per cubic foot. The exchange capacities of four artificial zeolites were found to vary inversely with the particle size. LITERATURE CITED (1) Bird, P. G . ,IND. ENO.CHEM., 24,793(1932). (2) W.S. Tyler Company. Cleveland, CutaZog 53,37 (1927).
R~CEIVED October 17, 1932.
CORRECTION. An error has been found in the article on “Compression Stress Strain of Rubber” by J. R. Sheppard and W. J. Clapson [IND.ENQ. CHEM.,24, 783 (1932)l. In the second column, in the sentence directly under Equation 5, “Equation 4” should read “Equation 5,” and vice versa. The corrected sentence then becomes: “Equation 5 defines the compressive force as a function of the equivalent tensile and of the new (diminished) length in the direction of compression when the original (unstrained) specimen is a cube of unit length; Equation 4 defines the compressive force in terms of the equivalent tensile.* * *”
