Chemistry and Physics. 277 



tal> were present. The paper, after stating that gutta percha was the 

 concrete juice of a large tree of the same name, abounding in Borneo, 

 &c, obtained by tapping the tree periodically by the Malays, stated 

 that its introduction into this country was purely accidental ; Dr. Mont- 

 gomery having transmitted the first sample of it to the Society of Arts 

 in 1843, at which time he (Mr. Whishaw) was secretary to that Society. 

 The first articles of use made of gutta percha in this country were laid 

 before the Society of Arts in 1844, and consisted of a lathe-band, a 

 short length of pipe, and a bottle-case, which he had himself made by 

 hand, having caused the concrete substance to become sufficiently plas- 

 tic by immersing it in hot water. He also produced casts from medals, 

 which attracted considerable attention at the time, and surgical instru- 

 ments were soon after made of this new material. It was also adapted 

 to commercial uses ; and from the period mentioned to July 11th in 

 the present year, between six hundred and seven hundred tons had 

 been imported for the Gutta Percha Company. From twenty to sixty 

 tons were now regularly imported every month. Contrary to the gen- 

 eral opinion that gutta percha is a simple, hydrogenous substance, Mr. 

 Crane (chemist to the Gutta Percha Company) found it in its ordinary 

 state to consist of at least two distinct materials, besides a notable pro- 

 portion of sulphur — viz., 1. A white matter, gutta percha in its pure 

 state; 2. A substance of dark brown color. Various experiments were 

 made to ascertain its strength when mixed with other matters, and also 

 as to what pigments would mix with it without rendering it brittle or 

 deteriorating its qualities. From these it appeared that the only pig- 

 ments that could altogether be relied on to be used with gutta percha 

 were orange lead, rose pink, red lead, vermilion, Dutch pink, yellow 

 ochre, and orange chrome. Under the influence of heat and pressure, 

 gutta percha would spread to a certain extent, and more so if mixed 

 with foreign matters. All the mixtures composed of gutta percha and 

 other substances which had been subjected to experiment, except that 

 containing plumbago, were found to increase its power of conducting 

 heat; but in its pure state, gutta percha was an excellent non-conductor 

 of electricity. The best composition for increasing the pliability of 

 gutta percha was that formed in conjunction with caoutchouc tar, and 

 next in order that of its own tar; and the best material at present 

 known for moulding and embodying was obtained by mixing gutta 

 percha with its own tar and lamp-Mack. 



In describing the process of manufacturing gutta percha, the author 

 observed, that rude blocks of the material were first cut into slices, by 

 *neans of a cutting machine formed of a circular iron plate of about 

 five feet in diameter in which there are three radical slots furnished 

 with as many knives or blades. The blocks are placed in an inclined 

 shoot, so as to present one end to the operation of the cutters. The 

 slices are then placed in a wooden tank, containing hot water, in 

 which they are left to soak until found in a plastic state. They are 

 afterwards passed through a mincing cylinder, similar to that used in 

 paper mills for the conversion of ragfl into pulp, and then thoroughly 

 cleansed in cold water tanks ; the water, in cases of impure gutta per- 

 cha, being mixed with a solution of common soda or chlorid of lime. 

 It is n rt put info a masticating machine, such as is used in the manu- 



