Directions for use are as follows:  “Take the battery out of the pocket and saturate it in good vinegar for about ten minutes for the first time, and after that five minutes each time before wearing.  To make sure that it has been thoroughly charged, touch the positive plate to the tongue, and place the negative plate between the eyes, when the electric flash will be felt and seen, if in the dark.  It is best to have the plates covered with wet flannel so that the tingling sensation of the current entering the body can be felt.”