134 STERILIZATION AND DISINFECTION 
zinc and tin. The action was found to be the same for both polished 
and corroded metal. Such data are interesting when it is remembered 
that some of these clements are used for the manufacture of toilet 
articles and mouth pieces for public drinking fountains. Under these 
conditions a disinfecting action could hardly be expected. Bacteria 
will exhibit great development in cultures containing the heavy metals 
in large pieces. 
Halogens. The halogens have rather important positions as dis- 
infectants. Chlorine has had much use as an internal disinfectant in 
diphtheria, scarlet fever, etc. It is contained in water in a concen- 
tration of about 0.4 per cent. The action of chlorine is generally 
admitted to be an oxidation reaction. Recently it has replaced bleach- 
ing powder in the treatment of public water supplies. It is distributed 
in the liquid form and has many advantages over calctum hypochlorite. 
Bromins. ‘This is used asa saturated aqueous solution containing 
about 3 per cent of the element. When used internally the strength 
of the solution must be greatly reduced to contain about 0.8 per cent 
It is a strong oxidizing agent and readily attacks metals. This places 
some limitations on its use as a disinfectant. 
Iodine. A 5 per cent solution with 10 per cent of potassium iodide 
is a reliable disinfectant. It is available as a tincture which is an 
alcoholic solution of the element. It is soluble in alcohol to the extent 
of about 1 part in 10. Free iodine exerts a powerful toxic action on 
bacteria since it unites directly with the bacterial protoplasm. Iodo- 
form is an iodine compound (CHIs) used in disinfection. It is applied 
directly to wounds and unites with the organic matter. Free iodine 
results and iodoform owes its action io the iodine which is thus given 
off. Often it is made into an ointment by mixing with some carrier. 
Other forms of iodine which may be used as antiseptics are: 
Iodoformogen—iodoform albuminate. 
Todo-Hemol Merck—Iodized hemol. 
Iodol—(C4H4NH) iodocarbamid. 
Todomuth—Bismuth iodine compound. 
Mahon and White (1915) report that iodine in alcohol is about four 
times as powerful as a disinfectant as phenol. Their work was done 
on naked organisms with B. typhi as the test organism. Eugling (1912) 
in studying the germicidal action of iodoform could not detect a reduc- 
ing action of bacteria resulting in the liberation of free iodine. 
Silver Salts. Silver precipitates proteins from solution as insoluble 
salts. It probably acts in the same way on bacterial protoplasm. 
