| ℞ | Paraffin (plate, sterile) | ʒij; |
| Vaselin alba (sterile) | ℥ij. |
The two are placed into a porcelain receptacle and melted in a hot-water bath to the boiling point, then thoroughly mixed by stirring with a glass rod and poured into test tubes of appropriate size and allowed to cool. Each tube is sealed properly with a close-fitting rubber cork, which may be coated with a liquid paraffin without, including the neck of the tube, and put away for later use.
Since 1905 the author has used an electrothermic heating device in which the paraffin mixture is prepared. The apparatus is made up of a metal pot set into a resistance coil, and is shown in [Fig. 286].
Fig. 286.—Author’s Electrothermic Paraffin Heater.
This instrument overcomes the complications of the water bath and burning or browning of the paraffin mixture, so commonly found with ordinary methods, the temperature of the resistance coil within the heating chamber being controlled by a small rheostat at will.
Before using, the contents of each test tube thus prepared are reheated to sterilization and poured into the barrel of the syringe to two thirds of its length, the piston introduced and screwed down into position; the syringe being placed to one side until its contents have been cooled, or the entire instrument is immersed in sterilized water at about 70° F. until the paraffin mixture has set or becomes uniform in consistency, which takes about five minutes.
Upon screwing down the piston the mass will be found to issue from the needle as a white, cylindrical thread, and is ready for use in this form.
Harmon Smith has had such a paraffin prepared which has a melting point of 110° F. This can be purchased in the market in sterile sealed tubes ready for use. The contents of these tubes should, however, be resterilized at the time of employment.