CHAPTER XVIII.
MISCELLANEOUS.
To Soften and Restore India Rubber Hose, etc.—I. Dip in petroleum and hang up for a couple of days. Repeat process if necessary.
II. The above process is applicable to all articles, but is specified for hose. It is stated that old rubber that has become hard may be softened by exposure first to vapor of carbon disulphide, followed by exposure to the vapor of kerosene. The latter vapor is found to be a general preservative for india rubber.
III. Dr. Pol recommends immersion in a solution of water of ammonia, 1 part, and water 2 parts, from a few minutes to an hour.
To Prevent Decay of Rubber Tubing.—The decay of rubber tubing has been attributed to the formation of sulphuric acid from the sulphur mixed with it. M. Ballard has suggested washing with water or weak alkaline solution five or six times in a year.
Joints between India Rubber Tubing and Metal.—Where tubing is temporarily slipped over metal gas pipes and similar connections, as in the chemical laboratory, it is well to apply glycerine to the metal. It acts as a lubricant in slipping the tubing on, and assists in its withdrawal.
Preserving Vulcanite.—Wash occasionally with a solution of ammonia and rub with a rag slightly moistened with kerosene oil.
Effect of Copper upon Rubber.—In a paper read before the recent meeting of the British Association, Sir William Thomson stated that metallic copper, when heated to the temperature of boiling water, in contact with the rubber, exerted a destructive effect upon it. With a view to finding whether this was due to the copper per se, or to its power of conducting heat more rapidly to the rubber, he laid a sheet of rubber on a plate of glass, and on it placed four clean disks, one of copper, one of platinum, one of zinc and one of silver. After a few days in an incubator at 150° F., the rubber under the copper had become quite hard, that under the platinum had become slightly affected and hardened at different parts, while the rubber under the silver and under the zinc was quite hard and elastic. This would warrant the inference that the metallic copper had exerted a great oxidizing effect on the rubber, the platinum had exerted a slight effect, while the zinc and silver respectively had no injurious influence on it. The rubber thus hardened by the copper contained, strange enough, no appreciable trace of copper; the copper, therefore, presumably sets up the oxidizing action in the rubber without itself permeating it.
Gas Tight Tubings.—Fletcher has invented a gas tight rubber tubing in which a layer of tinfoil is interposed between two concentric rubber tubes, all vulcanized together.
Printing Colors upon India Rubber.—It may sometimes be desirable to have a surface of vulcanized india rubber so prepared that it will take colors such as are used for calico printing. This end is simply attained by sprinkling the article with farina before vulcanizing. A small quantity attaches itself and forms an excellent base for color printing.