4Q2 COLLOIDS IN BIOLOGY AND MEDICINE 



In accordance with this, lysol acts twice as powerfully against 

 diphtheria bacilli as does /3-naphthol, whereas it has only one-tenth 

 the effect of the latter on B. coli. He showed further that a mixture 

 of tri- and tetrabrom-/3-naphthol in one per cent solution killed staphy- 

 lococci in from two to three minutes, whereas lysol dilutions containing 

 one per cent cresol took more than ten minutes to do so. Conversely, 

 a 5 per cent lysol solution containing 2.5 per cent cresol is lethal 

 for tubercle bacilli within four and a half hours, whereas a solution 

 of tri- and tetrabrom-/3-naphthol of corresponding strength had no 

 effect even at the end of twenty-four hours. We see, therefore, 

 that tri- and tetrabrom-/3-naphthol surpass cresol in its action upon 

 streptococci, while upon tubercle bacilli the cresol acts more power- 

 fully. H. BECHHOLD * 9 examined naphthols containing 1, 2, 3 or more 

 bromin or chlorin atoms with reference to their effect on various 

 bacteria. He found, that with the admission of the halogens the 

 effect upon various bacteria sometimes increased, that at times it 

 decreased, and that certain optima could be obtained (see Fig. 52 on 

 page 392). Thus the maximum disinfectant action against staphy- 

 lococci is obtained with tri- and tetrabrom-jS-naphthol, 1 while for B. 

 paratyphoid it is obtained with dibrom-/3-naphthol and so on. EISEN- 

 BERG has recently determined partly specific activities for a large 

 number of coal-tar dyes. 



It follows from this that to test an antiseptic on only one kind of 

 bacteria is an absolutely inadequate method for testing disinfectants; 

 it is necessary to subject a number of different types of bacteria to 

 investigation. 



The presence of a third substance is a factor in the action of a 

 disinfectant that cannot be neglected. We have already called at- 

 tention on page 383 to the influence of the solvent. To PAUL and 

 KRONIG, as well as to SCHEURLEN and SPIRO, belongs the credit of 

 having made clear the significance of electrolytic dissociation for 

 disinfectant action. Dissociation may be increased or diminished 

 by adding certain substances to the disinfectants. The ionization 

 of HgCl 2 is decreased by the addition of NaCl, and since it is the Hg 

 ion which is of importance in disinfection, the addition of common 

 salt diminishes the disinfectant action of sublimate. On the other 

 hand, the disinfectant action of carbolic acid, cresol and the other 

 phenols is decidedly increased by common salt. Since NaCl can 

 have no effect on the electrolytic dissociation of phenols, we must 

 seek some other explanation. Again, the nearest comparison must 



1 Tribrom-jS-naphthol is sold under the trade name " providoform " by the Pro- 

 vidogesellschaft (Berlin) and has proven useful in connection with the pus cocci 

 and diphtheria bacilli. 



