INDUSTRIAL AND ENGINEERING CHEMISTRY
MAY, 1937
as estimated colorimetrically, were 3.8 and 4 for I A 2 j and IIINAs, respectively. Phenol coefficients of the two fractions under consideration were redetermined with care, using E . typhi as the test organism a t 20’ C., and were found to check the values previously listed. In these tests dilutions were prepared in volumetric flasks rather than in the medication tubes: Conditions
a
Aqueous dilutions Aqueous dilutione Aqueous dilutions Aqueous dilutions 20% horse serum G r o n t h observed in
Temp.
c.
Test Organism
Phenol Coefficient
llrnAr
20 E . typha 7 0 17.0 37 E. typhz 7 5 11.9 20 Staph. aureus” 4 3 37 Staph. aureus 0 27 44 37 E. typhi 69 8 8 tubes containing 1: 25 dilution of the base.
Inhibition Tests Employing Solid Media The mycostatic tests described were carried out according to standard procedure (4). Preliminary tests were made emulsified in agar medium. The using the free 1.427 and IIINA~ tubes, cooled in slants, were streaked with a 4-mm. loop holding a broth culture. Under these conditions growth of E. typhi and Staph. aureus was not inhibited. The inhibiting action of base emulsions formed in situ from the hydrochloride solutions was also studied. One cubic centimeter of various dilutions was added to sterile test tubes with subsequent addition of 5 cc. of beef extract agar. The content of the tubes was thoroughy mixed and then allowed to harden in slants. Phenol dilutions were made up in an analogous manner, thus affording a basis of comparison. Blank tubes containing only agar medium served as controls. The slants were streaked with a 4-mm. loop as uniformly as possible. The results in Table VI refer to a 48-hour incubation period. TABLEVI. Stock Dilution
INHIBITION TESTSUSINGE. typhi AND Staph. aureu~ Final Dilution
E. ?uphi
Slaph. aureu8
1:600 1:7200 1:7800 1 :8400 1 :9000 1 : 10,800 1:12,000
Complete inhibition Normal growth Normal nrowth Normal growth Normal growth Normal growth Normal growth
Complete inhibition Complete inhibition Comnlete inhibition Complete inhibition Slight growth Slight growth Slight growth
1 :360 1:420 1 :480 1 :540 1:600 1:660
Complete inhibition Complete inhibition Complete inhibition Slight growth Slight growth Normal growth
Slight growth Slight growth Slight growth Normal growth Normal growth Normal growth
IAZ?:
1:lOO 1:300 1:400 1:500 11rNA6: 1:lOO 1:1200 1:1300 1 :1400 1:1500 1 :1800 1:2000 Phenol: 1:60 1:70 1:80 1:90 1:100 1:llO
1:600 1:800 1:2400 1:3000
505
filter paper 6 mm. in diameter. Again 1 ~ 2 was 7 without effect showed a clear zone in dilution of 1to 100. However, IIINAL in 1 to 100 dilution and a faint clear zone a t 1 to 1400 dilution.
Discussion of Results Under the conditions of the tests carried out in this general survey, the nitrogen bases compare favorably with phenol. A resume of the inhibition experiments brings out the fact that growth of E. typhi of standard virulence is completely inhibited by I A 2 j and IIINA~ in dilutions of 1 to 600, as com~ ineffective 7 pared with 1 to 480 for phenol. Although 1 ~ was against Staph. aureu8 in the usual germicide tests, it inhibits the growth of the organism in dilution of 1to 600. Likewise, 1 1 1 ~ is~ highly 5 efficient in this respect, inhibiting completely the growth of Staph. aureus in a dilution of 1 to 8400. The exact nature of the action of the solutions against bacteria was not investigated. Experiments with ordinary emulsions of the free bases showed no appreciable germicidal action. Also it may be pointed out that emulsions of free bases in agar medium possess no inhibiting action against the bacteria used. However, in all of the phenol coefficient determinations a very pronounced turbidity, due to liberation of free bases, takes place upon addition of the broth culture. The buffer action of the peptone evidently takes up the hydrochloric acid, liberating the bases in a finely dispersed state. With respect to the inhibition tests, a similar action occurs with the broth-agar medium. The molten agar becomes perfectly opaque because of the liberated bases, yet inhibitory action is quite pronounced. Thus it would seem that an extremely fine emulsion is germicidal, whereas the macrodroplets produced by agitating the bases with soap solution are without effect.
Literature Cited (1) Armendt and Bailey, J. Am. Chem. Soc., 55, 4145 (1933). (2) Biggs and Bailey, Ibid., 55, 4141 (1933). ( 3 ) King and Bailey, Ibid., 52, 1245 (1930). (4) Kolmer and Boerner, “Approved Laboratory Technic,” p. 427, New York, Appleton-Century Co., 1931. (5) Lackey and Bailey, J. Am. Chem. Soc., 56, 2741 (1934). (6) Lake and Bailey, Ibid., 55, 4143 (1933). ( 7 ) Patterson and Frederick, AnaEyst, 56, 93 (1931). ( 8 ) Perrin and Bailey, J. Am. Chem. SOC.,55, 4136 (1933). (9) Poth, Schulze, King, Thompson, Slagle, Floyd, and Bailey, Ibid., 52, 1239 (1930). (10) Thompson and Bailey, Ibid.. 53, 1002 (1931). (11) Zinsser and Bayne-Jones, “Textbook of Bacteriology,” p. 1144, New York, Appleton-Century Co., 1934. RECEIVEDDecember 21, 1936.
Correction Tests on Heavily Seeded Agar Plates The usual beef extract peptone agar was employed. Each plate contained 0.2 cc. of a 24-hour broth culture and 15 cc. of the agar medium. The base dilutions were applied by means of a single streak of a 2-mm. loop, and the readings were taken after a 48-hour incubation period. The plate containing E. typhi streaked with 1 . 2 7 showed only a faint clear zone, and the Staph. aureus plate streaked with the same dilution remained unchanged; in contrast, the 1 to 100 dilution of I I I N A 6 gave well-defined clear zones in both the E. typhi and Staph. aureus plates. Phenol dilutions of 1 to 90, 1 to 100, and 1 to 110 were applied in like manner without any observable effect on the bacterial growth. In an additional test with Staph. aureus the germicides were applied to the heavily seeded plates through a saturated circular
In the February, 1937, number of INDUSTRIAL AND ENGINEERING CHEMISTRY a drawing of the famous Count Rumford, by James Gillray, appeared as No. 74 in the Berolzheimer Series of Alchemical and Historical Reproductions. To the notes on page 166 accompanying this picture of Count Rumford and his stove, the following correction should be made: That phase of the versatile count’s scientific and technical work which has greatest significance is his study of the nature of heat; his classic determination of the amount of heat produced in boring cannon demolished at one stroke the theory of the materiality of heat and, aved the way for the first law of thermodynamics. The famiEar Rumford phosphate baking powder is so called because the inventor, Eben Horsford, was a Rumford Professor at Harvard University, t o which the count bequeathed the bulk of his estate. C. D. LOWRY, JR. UNIVERSAL OIL PRODUCTS COMPANY CHIOAQO,ILL. March 5, 1937
