136 DISINFECTION 



Hitherto, the dye treatment of wounds has not fulfilled the expectations of its 

 advocates, probably because the dyes can seldom be present continuously in 

 sufl&cient concentration in every part of the wound to inhibit bacterial growth 

 completely. As Browning (1933) points out, the destruction of organisms in 

 the centre of masses of necrotic tissue or blood clot is probably beyond the power 

 of any disinfectant. Moreover, many of the dyes inhibit leucocytic activity and 

 cause damage to the tissues (see Fleming 1940, Russell and Falconer 1941, 1943, 

 Manifold 1941, Rubbo et al. 1942, Russell and Beck 1944). They may, however, 

 have some value in the temporary prevention or control of infection (see Mcintosh 

 and Selbie 1942, Browning 1943). 



Essential Oils. — Chamberland (1887) tested the disinfectant action of a large 

 number of essential oils, by exposing anthrax spores and anthrax bacilli to their 

 vapours in closed tubes. After 4 days' exposure at 37° C. only one oil was suc- 

 cessful in killing the spores — namely, oil of Ceylon cinnamon. Anthrax bacilli, 

 contained in blood, were killed by oil of vespetro in 18 hours at 37° C, in 40 hours 

 by oil of angelica, and in 65 hours by oil of Ceylon cinnamon. Other oils the 

 vapours of which were germicidal, though less actively so, were oil of geranium 

 and oil of marjoram. 



He then tested the effect of the oils in a solution of alcohol and saponin. By 

 this method he found the most active in killing anthrax bacilli were oils of mar- 

 joram, cinnamon, sandal-wood, clove, juniper, and Artemesia annua. He draws 

 attention to the fact that cinnamon and marjoram oils are strongly active both 

 in the gaseous and in the liquid state. Similar observations were made by Cadeac 

 and Meunier (1889). They worked with Sahn. typhi and Pf. mallei, which were 

 allowed to remain in contact with the pure oil for a given time, and then seeded on 

 to agar. Table 14 shows some of their results. 



TABLE 14 

 Tr&iE NECESSARY TO KILL Salm. typhi. 



Many other oils did not kill fpr 24 to 48 hours, some not for 4 to 10 days, and 

 some not even in 10 days. Garlic vapour has quite a strong bacteriostatic, and 

 even a moderately germicidal, effect (see Bocker 1938). 



It will be seen that certain of the essential oils, if applied pure, are fairly active 

 germicides. The majority, however, are more valued for their antiseptic than 

 for their disinfectant action. For this purpose they were used extensively by 

 the ancient Egyptians in the process of embalming, with results which can be 

 seen at the present day (see Risler 1936). 



Vegetable oils that have no germicidal action themselves deprive other germi- 

 cides, which are dissolved in them, of most of their activity ; in this respect they 

 resemble alcohol. Koch, for example, found that phenol dissolved in vegetable 

 oils, such as olive or cotton-seed oil, was only slightly active. McMaster (1919) 

 has since confirmed this, but has pointed out that mineral oils do not have this 

 effect. Phenol dissolved in paraffin oil, for example, is nearly as active as when 

 dissolved in water. 



