by k. greh; SMITH. 341 



There is nothing new in this example of the influence of acidity 

 in increasing tlie activity of phenol, for Delepine* quotes an 



experiment showing that the presence of acetic acid in a solution 

 of phenol in the ratio of 1 : 400 ( = 41° of acidity) increased the 

 activity of the disinfectant by 140/70 in five minutes at 17". 

 Hydrochloric acid in the ratio of 1 : 8000 ( = 3-4°) increased it 

 by 80/70 in the same time. Hailerf says that acids increase the 

 disinfecting power of phenols in the order oxalic, sulphuric, 

 acetic, tartaric, citric, boric; the last has scarcely any action. 

 As having a bearing upon the matter, it is known that a faint 

 acidity causes a medium to be easily sterilised by heat. Currie, 

 for example, added 4 c.c. of seminormal hydrochloric acid per 

 litre to obtain the sterilisation of a saccharose medium in one 

 steaming. 



d. Water increases the efficiency of the oils. —The value of water 

 in enhancing the germicidal effect of cineol and reasonably of 

 Eucalyptus oils, is shown by the fact that B. colt communis, 

 when suspended in serum, was destroyed by a 50% dilution of 

 cineol in olive oil where the only water present was contained in 

 the serum. When an aqueous dilution of cineol was given the 

 same time to act, the bacteria were destroyed in a dilution of 

 1 :415, i.e., 50%, with a trace of water and 24% with much 

 water. 



An experiment was designed to see in how far bacteria im- 

 pregnated on cotton could survive the vapour of cineol at ordin 

 aiy temperatures (23° to 26 C, C), the idea being to determine if 

 cotton masks such as were worn during the pneumonic; influenza 

 epidemic would be sterilised when enclosed in a vessel containing 

 cineol vapour. Some strands of cotton were infected with seven 

 milligrams of C'/i-infected broth, and immediately suspended in 

 cineol vapour (see p. 91); others were dried in the air for an 

 hour before being suspended in the same manner. The moist 

 strands were found to be sterile in 60 minutes, while the dry 

 strands were sterile in three but not in two days. Obviously, if 



* Journ. Soc. Chem. Ind., 1910, 1344. 

 rAbstr. Journ. Soc. Chem. Ind., Kilo, .~>14. 



