Dr. Pereira's Elements of materia medica and therapeutics : abridged and adapted for the use of medical and pharmaceutical practitioners and students and comprising all the medicines of the British Pharmacopœia, with such others as are frequently ordered in prescriptions or required by the physician / edited by Robert Bentley and Theophilus Redwood ; with an appendix.

  • Jonathan Pereira
Date:
1874
Catalogue details

Licence: Public Domain Mark

Credit: Dr. Pereira's Elements of materia medica and therapeutics : abridged and adapted for the use of medical and pharmaceutical practitioners and students and comprising all the medicines of the British Pharmacopœia, with such others as are frequently ordered in prescriptions or required by the physician / edited by Robert Bentley and Theophilus Redwood ; with an appendix. Source: Wellcome Collection.

    1106/1180 (page 1074)
    [1074] Habitat.—A native of Borneo, Sumatra, and other Eastern Islands. It was formerly found at Singapore, but this is no longer the case. [§ Gutta-Percha. Gutta-percha. The concrete juice of Isonandra gutta (Hooker, London Journal of Botany, 1847). Characters and Tests.—In tough flexible pieces, of a light brown or chocolate colour. Soluble or nearly soluble in chloroform, yield- ing a more or less turbid solution.] Preparation and Commerce.—In order to obtain the milky juice the Malays have adopted the extravagant and wasteful method of felling the trees ; the bark is then stripped off, and the milky juice collected and poured into a trough formed by the concave stalk of the plantain-leaf, cocoa- nut shell, or some other suitable and readily obtained material. The juice quickly coagulates on exposure to the air. The average quantity yielded by each tree is 20 lbs., and as the annual importation of gutta-percha into this country is more than 40,000 cwt., it follows that about 220,000 trees must be annually destroyed for the English market alone. Such a wasteful mode of obtaining this substance must ultimately result in the entire destruc- tion of this tree in all its habitats, in the same manner as has already taken place at Singapore. It is probable, however, that other species of Isonandra also yield gutta-percha. Gutta-percha is imported in blocks weighing five or six pounds each; these are purified by cutting into slices, which are softened in hot water, and afterwards torn into shreds by rapidly revolving cylinders. These shreds are then thrown into cold water, and agitated, when the impurities sink, and the gutta-percha floats on the water. The gutta-percha is subsequently collected, placed in hot water, and whilst in a softened state it is made into solid masses, which are afterwards kneaded by machinery to get rid of the con- tained water. General and Chemical Characters.—Gutta-percha has a density of 0*979. It is insoluble in water, sparingly soluble in absolute alcohol and ether, and partially soluble in boiling olive-oil. Ben- zene, sulphide of carbon, chloroform, and oil of turpentine readily dissolve it by the aid of heat. Alkaline solutions, acetic acid, hydrochloric acid, and hydrofluoric acid have no action on it; hence receptacles for holding the latter acid may be readily pre- pared from gutta-percha. It is charred by strong sulphuric acid, and converted into a yellow resin by nitric acid. By dry distilla- tion it yields very inflammable oils. Its most important quality, which renders it so useful in the arts, is the facility with which it