There are two methods of making rubber tubing. The pure rubber is treated with carbon bisulphide or benzine to form a dough, which is rolled out into thin sheets and then cut into strips. A strip is i-olled round a cylindrical mandrel the diameter of the tube required, the superfluous edges are cut straight along, and the freshly cut edges touched with rubber solution and pressed together. The rubber is uow cured either by soaking for the requisite time in a solution of sulphur chloride in carbon bisulphide, or by heating in a mixture of French chalk and sulphur to a temperature of about 140° C. The mandrel can afterwards be withdrawn.

Wired tubing is made in the same way, the wire serving in place of the mandrel. Some tubing is made by kneading between steam-heated rollers the uncured rubber with sulphur and inert materials, such as zinc oxide, French chalk, etc., and forcing it through a hole in a die in which is a plug the same diameter as the tube. The rubber tube is drawn away as fast as it is formed, then placed in French chalk and heated to 140° F. The core of catheters and similar things is an iron wire, which is withdrawn after curing.