Table 111.
Analysis of Known Soa Prepared in
S nthetic Detergent Mixture
& form
Type of soap, toilet soap. Synthetic detergent, sodium salt of a sulfonated amide of a straight-chain fatty acid) Determination Present Found Alcohol-soluble matter Alcohol-insoluble matter Synthetic detergent Soap Chlorides Fatty matter
%
%
72.1 27.9 23.4 46.6 2.1
72.0 27.7 23.3 46.5 2.2 0.0
0.0
are sodium salts of alkyl aryl sulfonates; D is the sodium salt of a sulfonated amide of a straight-chain fatty acid; E is the sodium salt of a sulfonated straight-chain hydrocarbon. I n order to guard against the possibility that results obtained by the proposed method on a mixture in bar form, rn opposed to mixtures reported in Table 11, might be incorrect,, an additional sample of known composition made up in bar form was analyzed. The results as given in Table 111 are of satisfactory accuracy. The figures given are on the anhydrous basis. ACKNOWLEDGMENT
The authors are indebted to R. C. Hughes and C. W. Schroeder (present address, Continental Foods Corp., Hoboken, N. J.) of this laboratory for their many helpful suggestions, and also to the following for suggested methods: Jay C. Harris, Monsanto
A
241
ANALYTICAL EDITION
April, 1944
Carr-Price Reagent Dispenser
LYLE A. S W A I N Pacific Fisheries Experimental Station, Vancouver, 6. C.
T
HE saturated chloroform solution of antimony trichloride, used in the chemical determination of vitamin A, must be kept under anhydrous conditions a t all times, and provision must be made for rapid dispensing of accurately measured volumes.
k -\
Chemical Company; Armour and Company; American Cyanamid and Chemical Corporation; General Dyestuff Corporation; L. F. Hoyt, National Aniline Division, Allied Chemical and Dye Corporation; and Colgate-Palmolive-Peet Company. They are indebted to Lever Brothers Company for suggesting the uee of 50% alcohol solution for dissolving the sample, and to J. H. Shipp and Harold Jones of E. I. du Pont de Nemours and Company for n suggested method of analysis and for supplying the sample of Pedersen’s reagent. LITERATURE CITED
(1) Biffen, F. M.,and Snek F. D., IND.ENQ.CHBY.,ANAL.ED., 7,234 (1935). (2) Bureau of Ships, Navy Department, Specification 51D7 (INT) (1 November 1942). (3) Flett, L., Chem. Eng. N e w , 20,844 (1942). (4) Harris, J. C., IND.ENG.CHEY.,ANAL.ED., 15, 254 (1943). (5) Hart, R., Ibid., 5, 413 (1933). (6) Ibid., 10,688 (1938). (7)Ibid., 11, 33 (1939). (8) Jamieson, G. S., “Vegetable Fats and Oils”, 2nd ed., p. 391, A.C.S. Monograph, New York, Reinhold Publishing Corp., 1943. (9) Pedersen, C. J., Am. D u e s t q Y Reptr., 24,137 (1935). (10) Percy, J. H., and Arrowamith, C. J., IND.ENG.CHEM.,ANAL. ED., 14, 151 (1942). (11) Ruckman, N. E.,Hughes, R. C., and Clarke, F. E., Soap, 19, NO. 1 , 21-3 (1943). (12) Sunde, C. J., Ibid., 19,No. 7,30 (1943). THE.views in this article are those of the authors and should not be construed as the o5cial views of the Navy Department.
An ordinary pipet is unpleasant to use with this solution and is slow in delivery. The apparatus described serves to solve the problem where a considerable number of determinations are to be made. A constant-level reservoir for the reagent (Figure 1, A ) consists of a 300-ml. flask (or other convenient size) with an angular bottom offset leading to a side-arm reservoir wide enough for insertion of a 10-ml. Luer hypodermic syringe. To fill the reservoirs the small one is stoppered and the solution is added to the large one, which is then securely stoppered. The liquid level in the small reservoir remains constant when liquid is withdrawn therefrom. The solution is removed in measured volume by a hypodermic syringe (Figure 1, B ) with needle removed, fitted with a brass collar which can be clamped on the syringe barrel. A wrapping of surgical tape on the barrel forms a firm cushion for the collar, Two vertical rods are soldered to the collar and the limiting distance to which the syringe plunger may be withdrawn is governed by a swiveling top bar which may be turned aside when the plunger is to be removed. A stopper around the barrel assures its suitable depth of immersion in the small reservoir and excludes contact between solution and atmospheric moisture. A pipet of similar principle but not suited t o the present purpose was described by Krogh (1). A paper which appeared after submission of this note includes another design of apparatus for the same purpose (2). For accurate measurement the plunger must be inserted in definite position of orientation with respect to the barrel. This is maintained by suitable markings on the syringe parts. Tests, using water, gave four successive delivery weights of 9.02, 9.05, 9.03, and 9.04 grams. KO tendency for the syringe orifice t o drip during transfer was encount,ered. The syringe should not be left overnight without washing, as there is danger of freezing due to deposition of antimony trichloride. Rubber stoppers should be changed periodically because of attack by the reagent. The solution should be kept in the reservoir only during its actual use to avoid possible contamination from the rubber stoppers. LITERATURE CITED
Krogh, A., IND.ENQ.CHEM.,ANAL.ED., 7, 130 (1935). (2) Oser, B. L.,Melnick, D., and Pader, M.. Ibid., 15,724-9 (1943). (1)
