It was found that the machine acted better if the rubbers were covered with bisulphide of tin or with F.
The rubber is of good quality, though, owing to the method of preparation adopted, the product is often impure and discoloured, and consequently usually brings a lower price than the best rubbers of commerce.
Reports on many of the lesser known rubbers have been published in the Bulletin of the Imperial Institute.
It is already certain that some commercial rubbers contain a variable proportion of a substance of the nature of caoutchouc, but having different properties.
Pernambuco rubber, as is the case with most rubbers coagulated by saline solutions, contains a large quantity of water.
Pierre changed places several times during the game, sitting now with his back to Natasha and now facing her, but during the whole of the six rubbers he watched her and his friend.
It passes between two rubbers made of leather, and is partly covered with two silk aprons which extend over quadrants of its surface.
Specimens of the best known and of many of the lesser known rubbers are included in the Colonial and Indian Collections and Sample Rooms of the Imperial Institute, and many of the authentic specimens have been chemically and technically examined in the Scientific and Technical Department of the Institute and commercially valued.