A N A L Y T I C A 1, E D I T I O N
258
method was submitted to an industrial laboratory for use. Using 20-gram samples of undigested material in the disk method with 20-mm. diaphragms, the variation they obtained on fifty-four samples of apple butter (ranging in arsenic trioxide content from 0.1 to 3.0 p. p. m.) compared to the Gutzeit determination run on a digested sample is shown in Table 111. TABLE111.
GUTZEITAND DISK METHODS
COMPARISON OF
DEVIATION SAMPLEB FROM GUTZEIT P. p. m. Ass03 1 +0.3 8 +0.2 18 $0.1
SAMPLES 14 12 1
DEVIATION GUTZEIT P. w. m. Ass03 0
FROM
E
RECEIVEDDecember 28, 1933
-0.2
Easily Made Gas-Washing Bottle =
ALFREDH. MCKINNEY
0.12 p. p. m
Probable error of a single determination = 0.6745 u = kO.08 p. p. m. = f0.0016 mg. Asz03
Small amounts of arsenic were quantitatively removed in the presence of relatively large amounts of antimony. A special absorption train (Figure 2) is necessary, however, when more than 30 mg. of antimony are present, as the single cuprous-chloride-saturated cotton plug is not efficient above that range. Excessive amounts of reducible phosphorus and sulfur compounds also require the special train unless they are previously oxidized with bromine water. Some examples of the recoveries of added arsenic in the presence of arsenic-free contaminants appear in Table IV. TABLE1V. RECOVERY OF ARSENICIN PRESENCB OF CoxTAMINAXTB
IMPURITY .Mo. -~. 500 Purified antimony trioxide 125 Same 125 Same 250 Same 250 Same 250 Same 250 Same 250 Same 500 Same 250 Sodium thiosulfate 250 Cop er chloride 250 L e a l acetate 50 Sodium hypophosphate
ASS08
ADD~D Ma. 0.005 0.010
0.010 0.020 0.020 0.020 0.020 0.040 0.005 0.005 0.010 0.010 0.010
As203
RECOVERED Ma. 0.005 0.011 0.008
0 * 020 0.022 0.020 0,020 0.038
0.005 0.004 0.010 0.010 0.010
Arsenic was quantitatively removed without previous digestion from dilute solutions of the following organic arsenicals having arsenic in the trivalent as well as the pentavalent form : Av. Tryparsamide Neoarsphena~nine Tricacodylates Carbasone Arsphenamine
D a v i s , G. H., Analyst, 56, 30 (1931). Dodd, A. S., Ibid., 53, 152 (1928). Dowzard, E., J . Chem. Soc., 79, 715 (1901). Harvey, T. F., Chemist and DTuggist, p. 188 (1905). Hill and Collins, Ibid., p. 548 (1905). Linsey, A. J., Analyst, 55, 503-4 (1930). Manley, C. H., Ibid., 54, 30 (1929). Smith, C. R., U. S. Dept. Agr., B u r . Circ. 102 (1912). (le) Stubbs, J. R., An&&, 52, 700-1 (1927). (17) Taber, W. C., J . Assoc. Oficial Agr. Chem., 13, 417 (1930); 14, 436 (1931). (18) Ward, T. J., Analyst, 55, 630 (1930). (19) White, John, Ibid., 52, 701-2 (1927).
(8) (9) (10) (11) (12) (13) (14) (15)
-0.1
Deviation from Gutaeit = 21 No. of samples = n Mean = gv = $0.04 p. p. m. Standard deviation = u =
Vol. 6 , No. 4
BY GUTZEIT Bv. BY DISK METHOD METHOD Mg./cc. Mg./cc. 0.0025 0.0020 0.0012 0.0010 0.0006 0.0004 0.0030 0.0036 0.0010 0.0012
Philadelphia Quartz Company, Philadelphia, Pa.
T
HE gas-washing bottle herein described is useful because of its par ease of construction and satisfactory performance. The requirements are a &foot (150-cm.) section of glass tubing, 4lpuia a glass cylinder, a rubber stopper, and a few grams of paraffin. The glass tubing is bent in the spiral form as shown so that it w i l l fit w i t h i n t h e g l a s s cylinder. At the bottom of the spiral, on the under side of the tubing, a hole is blown. This is best done i n a h o t flame with but gentle pressure, so that the hole will not be too small. When the apparatus is assembled with the paraffin loose within the jar, the jar is inverted and heated so that the paraffin makes a gas-tight seal around the stopper and protects the latter from attack by the liquid. In operation the gas to be washed passes down to the bottom of the central tube. As it starts up the spiral, liquid enters the tube through the hole so provided. The gas then passes up the spiral as small bubbles, acting as an air lift, the volume of the bubbles and the ratio of liquid to gas depending upon the design of the apparatus and the gas velocity. The gases remain in contact with the liquid from 10 to 40 times as long as they would if allowed to bubble unobstructed to the surface. In the laboratory of the Philadelphia Quartg Company, this bottle of home-made construction, has, in a period of four years, been found entirely satisfactory. It has been subsequently improved first by specifying a ground-glass stopper and finally by making it of one-piece glass construction. R ~ C E I V EApril D 14, 1934.
ACKNOWLEDGMENT The author is indebted to G. S. Bohart of this laboratory for his helpful suggestions concerning this method and also to L. G. Petree for conducting many check determinations by the Gutzeit method.
LITERATURE CITED Beck, J. E., Chem. Trade J . , 71, 870 (1922). Bird, Analyst, 26, 181 (1901). Bird, Chemist and D ~ u g g i s t p. , GOO (1901). British Pharmacopeia, Appendix VI, pp, 501-20 (1914) (5) Calif. Dept. of Agr., Monthly Bull. 22 (March, 1933). ( 6 ) Cribb, C. H., Analyst, 52, 701 (1927). (7) Crihier, J. J., J . Chem. Soc., 120, 653 (1921).
Stainless Steel Bomb in Oxygen Calorimeter A bomb made of stainless steel (18-8) has been in use in this laboratory for about 3 years. This bomb constitutes the essential part of an improved type of oxygen bomb calorimeter. Up to date 2593 samples of coal and 164 samples of heavy fuel oil have been burned in it. Although no linings are used, the beautiful mirror finish of its inside surface has not been dulled in the least. It appears to resist corrosion perfectly. FREDF. FLANDERS State Purchase Laboratory Boston, Mass.
