No better antiseptic exists than ordinary soap, not altogether because of the properties of the soap, but because of the action of the soap combined with hot water. Washing soda, dissolved in water and used for boiling clothes which have become polluted, adds to the disinfecting power of the hot water the disinfecting properties of the soap, and the result is most effective. Ammonia has not the same value as the soda or potash soap, although it has the power of destroying bacteria in the course of a few hours. It may not be out of place to emphasize the value of soap, not particularly in times of epidemic or contagious disease, but as a continual safeguard against infection. A large proportion of the contagious diseases are probably the result of infected fingers or hands coming in contact with the mouth and leaving there the germs of infection. One of the first things a surgeon learns, in order to avoid any possible infection of wounds or of openings which he makes for an operation, is to thoroughly wash his hands in order to remove therefrom all possible germs. He scrubs his hands, particularly his finger nails, with soap and water and then bathes them in a solution of bichloride of mercury before touching the patient in any place where infection might occur. The difficulty, even with this great care, of freeing their hands from bacteria has been found to be so great that, in late years, surgeons have preferred to use, during operations, thin rubber gloves which can be boiled before using and can be soaked in a stronger antiseptic than the hands could bear. It is extraordinary, from the standpoint of self-infection, to see how men can be so careless as to sit down to dinner, after having worked in places where their hands have come in contact with all sorts of organic filth, without stopping to wash those hands even in cold water. It is certainly providential that disease germs are as uncommon as they are, for with the careless habits of most people in putting their hands to their mouths, the death-rate from infectious diseases would be much higher than it is except for the fact that most of the germs thus introduced into the mouth are not disease-producing. _Disinfecting by heat._ Better than any chemical agent known to be a destroyer of bacteria is heat in one form or another. This may be steam or hot water or dry heat. If a high enough temperature is maintained for a sufficient length of time, the action is absolutely destructive to all germs. Fire does, of course, destroy bacteria along with whatever material the bacteria are concealed in, but such a disinfectant is of little value for ordinary purposes, since the object of disinfection is to destroy bacteria without destroying the surface on which they are lodged. In some old buildings, where consumption or smallpox, for example, has become permanent, it may be that the surest way of killing all the bacteria is to burn up the house. _Dry heat._