Pseudo-Gutta Perchas, or Substances Supplementary to Gutta Percha.
(From the Indian Agriculturist. Reprinted from the Tropical Agriculturist.)
Foremost amongst pseudo-guttas, as we use the phrase, stands Balata gum. It is obtained from the Mimusops Balata of Gaertner (Nat. Ord. Sapotaceceae) and is synonymous with the Sapota Mulleri of Bleekrod, the Achras Balata of Aublet, etc. It is found in Demerara, Berbice, British and French Guiana, Antilles, Jamaica and Surinam. It has many vernacular names, amongst which may be mentioned, Balata, Paardenvleesch (Dutch-horse-flesh,) bullet-tree, etc.
One of the first writers on this substance was Professor Bleekrod, who communicated some information as to the plant and its product to the Society of Arts, in 1857. He, too, described the plant and named it Sapota Mulleri. In 1860. Mr. Walker communicated samples, etc., received from Dr. Van Holst, of Berbice, to the same Society, and in 1864 Sir William Holmes also drew attention to the same subject. The tree is a large one with a trunk of about 6 feet in diameter, and furnishes a wood much liked for building purposes and of the color of horse-flesh-hence the Dutch name. The bark is thick and rough, and the fruit is of the size of a coffee berry, sweet like a plum, and with a hard white kernel which yields a bitter oil.
The leaves are glossy, oval and accuminated. The milk is drunk by the natives, in cases of diarrhoea, and when diluted with water it is used as cow's milk. The trees grow in groups and in alluvial soil.
The "Balata" gum is of a character somewhat between caoutchouc and gutta percha, combining in some degree the elasticity of the one with the ductility of the other, freely softening and becoming plastic and easily moulded like gutta percha. What small parcels arrived in England met with a ready sale and were remarkably free from adulteration. But unfortunately, through the difficulty of collection—the undertaking being so dangerous and unhealthy—the supply of this excellent article has fallen off. It is collected by making incisions in the bark about 7 feet from the ground, and a ring of clay placed round the tree to catch the milk as it exudes. The yield is said to be in profusion especially at the time of the full moon, and the operation can be repeated every two months in the rainy season. It takes six hours to bring about coalescence by simple atmospheric influence, but very quickly by boiling in water. A large tree is said to yield as much as 15 lb. of "dry gum." The tree in every way is well worthy of a trial by acclimating it.
In India there are several plants whose products may be classed as pseudo-guttas. First and foremost of these we have the Pauchontee or India gutta tree, the Bassia elliptica of Dalzell the Isonandra acuminata of Lindley, but now known as Dichopsis elliptica. It is found in the Wynaad, Coorg, Anamallay and Neilgherry Hills, Sholah Forest, Cochin, Sichar, and according to General Cullen, "appears to be common in all the forest tracts at all within the influences of the southwest rains." This tree, which is now placed in the same genus as the true gutta percha, is a large one—from 80 to 100 feet high and was first met with by Mr. Dalzell, in North Canara, near the falls of Goirsuppah, in 1849. Since that date General Cullen and Dr. Cleghorn have used every exertion to bring the substance prominently forward but without success. The gum is obtained by tapping, 1½ lb. being obtained from one tree by five or six incisions, a large tree yielding as much as 20 to 40 lb. of sap. Many experiments have been made with specimens of the raw milk, i.e., milk simply dried by exposure to the atmosphere. The results of these experiments have shown that for telegraphic purposes it is wanting in some essential qualities, but it has been recommended as a subaqueous cement or glue. When dissolved in ordinary gutta percha solvents, it, after the evaporation of the solvent, remains some times soft and viscid, and partakes somewhat of the character of bird-lime. When cold, it is hard and brittle. Without wishing in the slightest degree to throw doubt or discredit on the many and valuable experiments made, we would suggest that good samples be collected and treated in the same manner as recommended for gutta percha. We have no doubt that many a parcel of what would otherwise be good gutta percha, is spoilt through not being well boiled immediately after collection from the tree. At present this is the only way in which we see there is a possibility of ascertaining whether this product can be utilized, and we have the more hope from the fact that the structural character has led the plant to be placed in the same genus as the true gutta percha—structural affinity agreeing so often to chemical affinity.
There are in India other nearly allied Sapotaceae which deserve attention in order to ascertain whether any of them yield a milky juice likely to be of commercial use. Amongst the Euphorbiaceae there are two plants worthy of notice. The Euphorbia Cattimandoo, found in various parts of India, was first brought to notice by the Honorable W. Elliot, and a prize medal was awarded for this substance by the jurors of the 1851 exhibition. This spiny euphorb grows to the size of a shrub or small tree, and the milk flows out freely when a branch is cut. The natives use it as a cement to fasten knives in handles, etc. Under the influence of heat it becomes soft and viscid, and when dry, very brittle. The Euphorbia Tirucalli, the milk hedge or Indian tree spurge, is a succulent unarmed plant attaining a height of 20 feet, and its inspissated milk is used for various-chiefly medicinal-purposes, and has been recommended as a gutta percha substitute, but like gum Euphorbium, it has a very acrid character, and the collection is a very dangerous operation to the eyes.—Phar. Jour., August 1883, p. 104.