Photographic reproduction from a booklet on “Thermozine” giving the conditions in which the stuff was alleged to be “very useful.”
The significant requirements of paraffin for surgical dressings are that it should be solid at body temperature, at the same time having flexibility and adhesiveness, together with a certain amount of strength. A number of brands of paraffin are sold in the United States, so that it seemed advisable to examine some of them and compare them with certain paraffin-film preparations. They were tested as to their melting points, plasticity, ductility, strength of film, etc.
Melting Point Determination.—The melting point was determined by the method of the U. S. Pharmacopeia IX, p. 596. The melting point as obtained by this method is lower than the melting point used by manufacturers of paraffin (after conversion to Fahrenheit).
Pliability and Ductility, Limit Temperature.[180]—A little of the melted wax was poured from a teaspoon on the surface of the water at about 40 C., in a tin pan (bread mold). This formed a fairly thin film. The temperature of the water was then lowered by the addition of cold water. At each temperature the pliability and ductility were tested thus:
Pliability Test.—The film, immersed in water, was doubled on itself, note being taken whether or not it broke.
Ductility Test.—The film was pulled under water, note being taken whether it stretched on being pulled and broke with a ragged fracture; or whether it broke sharp without stretching. It is desirable that the pliability and ductility be preserved at as low a temperature as possible.
Cotton Films, Adhesives and Detachability.[180]—The melted wax was applied as it would be for burns; namely, a thin layer was painted on the inner surface of the forearm with a camel’s hair brush,[181] a transverse strip about an inch wide being made. This was covered with a very thin layer of absorbent cotton, and over this another layer of melted wax was painted. As soon as this had cooled a little, it was covered by a few layers of bandage and left on for at least an hour. At the end of that time, the bandage was removed. The cotton film should be found at the place at which it was applied, showing that it is sufficiently adherent. It should detach without “pulling” the skin.
Photographic reproduction (greatly reduced) of the carton in which “Ambrine” is now sold.