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On the Conditions under which Discontinuous Events may be employed as a Measure of Continuous Processes, with Especial Reference to the Killing of Bacteria by Disinfectants

Published online by Cambridge University Press:  15 May 2009

T. Brailsford Robertson
T. Brailsford Robertson
Affiliation:
(From the Rudolph Spreckels Physiological Laboratory of the University of California.)
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It is shown that provided the total number of individuals exposed to a constant environment which is inducing change within them be constant, and the number of units of change which must take place within any given individual in order to cause a given event be also constant, then the number of these events is a quantitative measure of the extent of the change in all of the individuals taken together.

From this it follows that the results of Madsen and Nyman and of Chick may legitimately be regarded as proving that the process which underlies disinfection obeys the time-relations and other characteristics of a mono-molecular chemical reaction.

Type
Research Article
Information
Journal of Hygiene , Volume 14 , Issue 2 , July 1914 , pp. 143 - 148
Copyright
Copyright © Cambridge University Press 1914

References

page 144 note 1 Chick, H.. Journal of Hygiene, (1908) VIII. 92; (1910) X. 237; (1912) XII. 414.CrossRefGoogle Scholar

page 144 note 2 Madsen, and Nyman, (1907). Zeitschr.f. Hyg. LVII. 388.CrossRefGoogle Scholar

page 144 note 3 As far as we know Madsen and Nyman offered no interpretation of the facts they brought forward. (Ed.)

page 144 note 4 Udny Yule, G. (1910). Journal of the Royal Statistical Society, LXXIII. 26.CrossRefGoogle Scholar

page 146 note 1 In other words, that the underlying change does not cease with the death of the bacteria, i.e. that the bacteria remain uniformly suspended in the solution of the disinfectant even after death. This condition was fulfilled in the experiments under consideration. If the bacteria were for any reason removed from the sphere of action of the disinfectant at death, for instance by falling out of suspension, then N at any moment would be equal to N 1 − y, where N 1 was the initial number of bacteria exposed to the disinfectant. In other words, unless y were very small in comparison with N 1, N would vary with the time, and the time-relations observed by Madsen and Nyman and by Chick could not be obtained.

page 146 note 2 Cf. Udny Yule, G. (1911), An Introduction to the Theory of Statistics, London 1911, p. 289.CrossRefGoogle Scholar

page 146 note 3 Provided, that is, that the quantity of disinfectant used up in killing all of the bacteria was evanescently small in comparison with the total quantity of disinfectant employed. This condition was obviously fulfilled in the experiments to which I have referred.