Sponges can also be had at the drug store. They have a tap attached to
them to be conveniently removed. They should be soaked in an
antiseptic solution for a few minutes before coitus and then
introduced into the vagina far up as they can be placed. Some
physicians have recommended the use of the cotton plug, instead of the
sponge, to be soaked in a solution of three per cent carbolic and
glycerine, before the act. The male sperm is destroyed by the weakest
solution of carbolic acid. Some of the peasants in Europe use the
cotton plug soaked in vinegar for the same purpose and find it
satisfactory. In this country a boric acid solution has been used for
the same purpose and with satisfactory results. Of course this
requires a saturated solution, as, for instance, one teaspoonful of
the powder to a cup of water stirred until dissolved.
Sponges and plugs can be recommended as perfectly safe, if followed by
an antiseptic douche before the removal of the plug or sponge, thus
preventing the sperm from entering the womb. The problem is: to kill
the male sperm upon entering the vagina, or to wash it out or to kill
it directly afterwards. A weak solution of alum may also be used for
cotton plugs and sponges, _also carbolated vaseline on plugs_.