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.
Pernambuco rubber, as is the case with most rubbers coagulated by saline solutions, contains a large quantity of water.
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.
Reports on many of the lesser known rubbers have been published in the Bulletin of the Imperial Institute.
The proteids should be as far as possible removed during the preparation of the rubber, as these substances are chiefly responsible for the objectionable smell and colour of " native " rubbers, and their presence leads to subsequent change in the commercial material.
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