peh., 1916
THE JOURNAL
O P I ~ V D U S T R P A LA N D E N G I f i E l ? R I Y G C H E M I S T R Y
powder to a water containing calcium, magnesium and iron salts would cause the precipitation of calcium and magnesium fluorides and these by inclusion would carry down ferrous or ferric fluoride or both. Now, while it is true that both the ferrous and ferric fluorides are soluble in water it is also true that no amount of washing will free the gelatinous calciumand magnesium fluorides from the ferrous or ferric salts with which they are contaminated. As the calcium and magnesium fluorides are insoluble in water, and as this precipitation takes place in the presence of the fabric, and is also accelerated by heat, the pores of the fabric will retain, in spite of the rinse which follows, enough of the impure calcium and magnesium fluorides t o produce the discoloration in question. The trouble is caused, therefore, by the action of such a powder on hard water and will increase or diminish as the amount of iron in the water increases or decreases. Repeated washing will of course increase the discoloration. The detrimental effects of the precipitation of even perfectly white salts of such a nature in fabrics is too well known to require any comment, and the use of compounds producing them should be strongly discouraged. E. D. KOEPPING LOCKPORT, N E W YORK S o v e m b e r 16, 1915
NOTE ON “THE PHENOL COEFFICIENT OF GERMICIDES”
Editor of lhe Journal of Industrial and Engineering Chemistry: In THIS JOURNAL, 8 (1916), 45, there appears an article by Messrs. Kilmer, Clark and Hampton on the “Hygienic Laboratory Method for Determining the Phenol Coefficient of Disinfectants.” Their experimental results show that a coefficient of I 60 is obtained for Camphenol” in a series of tests in which the culture medium used for growing the test organism was composed of 3 grams of beef extract, 2 0 grams of peptone and I liter of water, while a coefficient of 3 2 0 was obtained when the medium contained 3 grams of beef extract, I O grams of peptone, 5 grams of salt and I liter of water. The authors say that they “are unable to offer any rational explanation” for the results. I t seems t o me that there are two factors involved. The first is the phenol used. An examination of Table I shows that the phenol was much more active, that is, that killing occurred a t zl/z and a t 15 minutes with higher dilutions, than in any published results with which I am familiar. I n experiments made in this laboratory with a similar medium (but a different make of phenol), the dilutions required for the zl/z-rninute period ‘ I
I
r97
were 1-80 or 1-90, and for the 15-minute period 1-100 or 1-1 IO. If 80 and I I O were used for calculating the coefficient, the result would be about 2.25. The use of different varieties of phenol would account, then, for a part, but only a part, of the discrepancy. The other, and more important factor involved is the presence of salt in the culture medium It is well known that salt accelerates the action of a disinfectant. Results obtained in this laboratory during the past two years show the extent of this acceleration very well. These results will appear shortly in the Journal of Infectious Diseases. I n the experiments described by Messrs. Kilmer, Clark and Hampton, 5 grams of salt were used per liter of medium, and o I cc. of this was used for the test experiments. There was thus p;esent in the j cc. of disinfectant o 5 milligram of salt Comparison of results on the killing power of “Camphenol” in Tables I and I1 shows that with the salt medium the disinfectant was 1.62 times as active in the 21/z-minute period and 1.67 times in the 15-minute, as when the medium containing no salt was used. While in the experiments made in this laboratory the amounts of salt were slight11 greater, still they were of the same order. We used formic acid for the disinfectant. When 1.0 milligram of salt was present in j cc., the disinfectant was found t o be 3 times as active as when no salt was present, and with I 2 milligrams of salt the disinfectant was 4 times as powerful. It will therefore be seen that a very small amount of salt will very greatly influence disinfection, and the increased activity of “Camphenol” as shown in Table I1 can be accounted for on this basis. It is not probable that every disinfectant is accelerated to the same degree by the presence of salt, but this could be fairly easily tested. If therefore, “Camphenol” was more sensitive to this accelerating action than was phenol, the phenol coefficient, as determined, would be higher. The main idea which I wish t o emphasize is that the salt content of the culture medium is a very important factor, and one which should not be overlooked in suggesting any standard medium for use with disinfectants. I believe also t h a t more than one discrepancy in phenol coefficient determinations can be accounted for by this factor-the salt either being a recognized addition to a medium in one case but not in another, or getting into the medium in varying amounts by the use of broth obtained from different sources, such as meat and the various meat extracts. MASSACHUSETTS INSTITUTE OF TECHNOLOGY JOHN F, NORTON BOSTON,January 13, 1915
PERSONAL NOTES
The United States Civil Service Commission announces an open competitive examination on February 23, 1916, for the position of chemist, for men only, a t a salary of $ 1 2 0 0 a year; also a n open competitive examination, on February 2gth,*for pharmaceutical research chemist, for men only, a t a salary of $3000 a year. Another Civil Service examination will be held on April 12, 1916, for the position of junior chemist, departmental service. These examinations are open t o all men who are citizens of the United States and who meet the prescribed requirements. Further information may be had by applying t o the United States Civil Service Commission, Washington, D . C. Dr. Charles R . Van Hise, President of the University of Wisconsin, has been elected president of the American Association for the Advancement of Science, in succession to Dr. W. W. Campbell. Charles M. Hall, inventor of the process for recovering aluminum which bears his name, who died December 27, 1914, left an estate valued a t $10,000,860, according to testimony of
A. V. Davis, of Pittsburgh, a n executor, before State Transfer Tax Appraiser Rice. The entire fortune was made in aluminum. Sir Henry Enfield Roscoe, F.R.S., the distinguished British chemist, emeritus professor j n the University of Manchester, died on December 18th, a t his residence in West Horsley, England, a t the advanced age of 81 years. A memorial service was held on December 22nd a t the Rosslyn Hill Unitarian Chapel. The first annual meeting of the Technical Section of t h e American Paper and Pulp Association will be held in n’ew York City a t the Waldorf-Astoria Hotel, February 16th and 17th. The committee meetings have been arranged for Wednesday, the general meetings of the Section being scheduled for the forenoon and afternoon of Thursday. The meeting in the afternoon will be attended by the proprietors of pulp and paper mills from all parts of the country, in addition to the chemists and engineers connected with the industry, who make up the membership of the Technical Section. It is planned to exhibit
