ANALYTICAL EDITION
76
Vol. 5 , No. 1
dues; and in following the course of decomposition of thin deposits of rotenone exposed to light and air, an adaptation rendered possible by the fact that the test is not given by the products of such decomposition. The testing of proprietary insecticidal preparations is an obvious use for this method. I n the case of dry powdered preparations the test may be made on an acetone extract.
Liquid preparations and extracts including oily samples usually respond to direct treatment with nitric acid.
‘Use of Kohlrausch Sugar Flasks in Determinations of Biochemical Oxygen Demand
LITERATURE CITED
IVANC. HALL
(1)
LITERATURE CITED Durham, H. E., quoted by Gimlette, J. D., “Malay Poisons and
Charm Cures,” 2nd ed., p. 221, J. and A. Churchill, London, 1923.
RBCEIYED
(1) Hall, I. C., J . Infectious Diseases, 29, 317 (1921). (2) Hall, I. C., University of California, Publications in Pathology, 2, 147 (1915). (3)
Pomeroy, J. L., and Stone, R. V.,
OHLRAUSCH sugar flasks were first advocated for putrescibility tests in 1928 by Pomeroy and Stone thus applying the principle of the constricted tube with marble seal devised by Hall (1, 2) in 1915. These flasks are equally suitable for biochemical oxygen demand tests and are much more convenient than the reagent bottles. It is difficult to replace stoppers in reagent bottles without trapping air bubbles, and more care is reauired with the reagent bottles in d i s p o s i n g safely of the excess of liquid f o r c e d o u t upon the addition of reagents, although these objections do not apply to the special flasks devised by Theriault (4, 6). With the Kohlrausch flasks air bubbles are also easily excluded; the excess of liquid is caught above the m a r b l e s e a l a n d c a n be e a s i l y dumped in the sink when the flask is inverted, with the finger holding the marble in place to mix its contents. The author has worked with flasks of 200.6 cc. calibrated capacity, holding about 225 cc. to the marble seal. The graduation is an advantage in me a s u r i n g samples for titration. During i n c u b a t i o n evaporation is minimized by means FIGURE1. KOHLRAUSCH SUGAR FLASK of an inverted beaker, as shown in WITH MARBLESEAL Figure 1. The flask has one disadAND BEAKER vantage, that its shape slightly delays thorough mixing as compared with bottles, and necessitates specialattentionin securing thorough diffusion of reagents. If Kohlrausch flasks should receive favor for these tests, an improved form with a short neck would overcome this one objection. In the writer’s experience the results of comparative determinations of biochemical oxygen demand on single samples showed less variation with flasks than with bottles, but further comparative studies are needed and particularly by those accustomed to using bottles.
Am. J . Pub. Health, 18, 1172
(1928). (4) (5)
Theriault, E. J., Pub. Health Bull. 173, 185 (1927). Theriault, E. J., Suppl. Pub. Health Repts., 90 (1931).
RDCDIVDD August 29, 1932. Presented before the Division of Water, Sewage, and Sanitation Chemistry at the 84th Meeting of the $merican Chemical Society, Denver, Colo., August 22 to 26, 1932.
Department of Bacteriology and Public Health, University of Colorado School of Medicine, Denver, Colo.
K (a),
November 2 5 , 1932.
A Continuous Extractor ARMANDJ. QUICK Cornell University Medical College, New York, N. Y.
T
H E usefulness of a continuous extractor, especially in the analysis of biological fluids such as urine and blood filtrates, is being gradually recognized, A form of extractor which the author has found highly satisfactory is given in the accompanying sketch. It consists of an outer jacket, J (length, 450 mm.; internal diameter, 32 nim.); an extraction tube, T (length, 280 mm.; internal diameter, 15 mm.), having a 5-mm. opening 45 mm. from the top of the tube; a funnel tube, F (length 340 mm.; external diameter 7 mm.), with a bulb a t the lower end containing four small openings; a condenser, C; and a 125-cc. Erlenmeyer flask. The extraction tube is suspended by means of a silk thread or a thin wire. This tube is designed for a sample of 20 cc. or less. A battery of six to eight extractors can easily be set up. At the completion of the extraction, the flask is removed, fitted with an ordinary distilling head, and the solvent removed by distillation. RECBIVED August 2, 1932.
INCREASED SHIPMENTS OF U. S. BIOLOGICAL PREPARATIONS TO PHILIPPINES. Modification by the Philippine Health Service of its regulations affecting the period of potency of biological preparations is expected to react to the advantage of American exporters of such products, according to the Commerce Department. Changes in the Philippine regulations bring them into line with the regulations of the United States Hygienic Laboratory. Formerly, European manufacturers could comply with the Philippine regulations because it usually meant only shortening their datings while American manufacturers, prohibited from lengthening their datings, found it difficult to compete.
