Collected papers . tant. 16—3 242 Disinfection Exp. TABLE III. Dism/ection of B. typhosus with 06 ^o phenol at 20° 1. 10. Amount Mean no. of Time, ofsample Numbers bacteria presentin 1 drop K= minutes taken, on plates disinfection -—log = t drops (gelatine) Mean mixture, =N Logio N t^ 0-o = to 1 779 717 645 714 1U = N, 2-854 — 1-5 1 584 571 577-5 577-5 2-762 •092 2-5 1 406 526 451 461 461 2-664 •095 4-5 1 313 215 288 272 272 2-435 •105 6-5 1 136 149 145 143-3 143-3 2-156 •116 10 2 47 162 155 121-3 60-6 1-782 •113 20 f 5 ho 3523 54 = 1 4-48 •651 Mean -113 •106 ^0 N„ both experiments. Disi
Collected papers . tant. 16—3 242 Disinfection Exp. TABLE III. Dism/ection of B. typhosus with 06 ^o phenol at 20° 1. 10. Amount Mean no. of Time, ofsample Numbers bacteria presentin 1 drop K= minutes taken, on plates disinfection -—log = t drops (gelatine) Mean mixture, =N Logio N t^ 0-o = to 1 779 717 645 714 1U = N, 2-854 — 1-5 1 584 571 577-5 577-5 2-762 •092 2-5 1 406 526 451 461 461 2-664 •095 4-5 1 313 215 288 272 272 2-435 •105 6-5 1 136 149 145 143-3 143-3 2-156 •116 10 2 47 162 155 121-3 60-6 1-782 •113 20 f 5 ho 3523 54 = 1 4-48 •651 Mean -113 •106 ^0 N„ both experiments. Disinfection, as in the case of anthrax spores,proceeded so that the number of survivors in unit volume varied logarith-mically with the time; the logarithms of these numbers, when plottedagainst time, also gave straight lines (Fig. 2). The velocity constant, K i = 7 log —-), calculated from the experimental numbers, is given in the last column of either table, and shows fair constancy Time, minutes Fig. 2. Disinfection of B. typhosus with 0-6 % phenol at 20° C.(a) Exp. 8. 1. 10, Table II. {b) Exp. 14. 1. 10, Table III. H. Chick 243 (b) Experiments with B. coli commune. Tables IV and V give the results of two experiments with B. colicommune and 0*5 7o phenol at 20° C, in the one case agar and in theother gelatine plates being used. 24 hours cultures in broth at 37 C.^ Disinfection of B. coliExp. 15. 2. 10. TABLE IV. commune with 0*5 Yo phenol at 20 C. Time, ninute = t Amount ofsample3 taken,drops Numbers on plates (agar) Mean Mean no. of bacteria present in 1 drop disinfection mixture, =N LogioiV t^ -t ^°^V (0-8 593 623 608 608 2-784) — 1-9 = «o 1 286 354 256 299 299 = iYo 2-476 — 2-9 229 219 301 249-7 249-7 2-397 -079 4-25 193 209 217 206-3 206-3 2-314 -069 5-75 192 172 158 174 174 2-240 -061 7-5 (2 127 261 II 129-3 2-112 •065 10 2 144 207 175-5 87-75 1-943 -066 15, !^ 121261 -1\ 47-7 1-678 •061 20 <10 116195 - \ - i 20-73 1-317 -0
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