GUTTA-PERCHA 771 



and coal-tar. A good cement for luting bottles and other purposes is formed by 

 boiling together equal parts of gutta and coal-tar and resin. When required for use, 

 it can always be made plastic by putting the pot containing it over the fire for a few 

 minutes. The gutta-percha itself is highly inflammable ; a strip cut off takes Alight, 

 and burns with a bright flame, emitting sparks, and dropping a black residuum in the 

 manner of sealing-wax, which in its combustion it very much resembles. But the 

 great peculiarity of this substance, and that which makes it so eminently useful for 

 maiiy purposes, is the effect of boiling water upon it. When immersed for a few 

 minutes in water above 150 Fahr. it becomes soft and plastic, so as to be capable of 

 being moulded to any required shape or form, which it retains upon cooling. If a strip 

 of it be cut off and plunged into boiling water, it contracts in size both in length and 

 breadth. 



It is this plasticity when plunged into boiling water that has allowed of its being 

 applied to so many useful purposes, and which first induced some Malays to fabricate 

 it into whips, which were brought into Singapore, and led to its further notice. The 

 natives subsequently extended their manufactures to buckets, basins, and jugs, shoes, 

 traces, vessels for cooling wines, and several other domestic uses. Its easy plasticity 

 and power of retaining any shape given to it when cool, at once pointed it out as 

 suitable for the manufacture of bougies; and accordingly Dr. W. Montgomerie 

 availed himself of this, made several of the above instruments, and recommended the 

 use of it to the Bengal Medical Board. It also answers very well for the tubes of 

 syringes, which are always getting out of order in hot climates, when made of 

 caoutchouc. 



Mr. T. Oxley, surgeon, Prince of Wales Island and Malacca, whose remarks 

 are of much value from his acquaintance with the production of which he writes, 

 says : 



'I observed in the " Mechanics' Magazine " for March 1847, a notice of several 

 patents taken out for the working of this article by Mr. Charles Hancock, in which an 

 elaborate process is described for cleaning the gutta, as also mention of its having a 

 disagreeable acid smell. The gutta, when pure, is certainly slightly acid, that is, it will 

 cause a very slight effervescence when put into a solution of soda, but is unaffected 

 by liquor potassse. The smell, although peculiar, is neither strong nor unpleasant, so 

 that the article experimented on must have been exceedingly impure, and possibly 

 derived a large portion of its acidity from the admixture and fermentation of other 

 vegetable substances. Again : it appears to me that, if the gutta be pure, the very 

 elaborate process described as being necessary for cleaning it, is superfluous. The 

 gutta can be obtained here in a perfectly pure state by simply boiling it in hot water 

 until well softened, and then rolling it out into thin sheets, when all foreign matter 

 can be easily removed. I would recommend that the manufacturers at home should 

 offer a higher price for the article if previously strained through cloth at the time of 

 being collected, when they will receive the gutta in a state that will save them a vast 

 deal more of trouble and expense than the trifling addition necessary to the original 

 prime cost.' 



In February 1847, Mr. Charles Hancock obtained a patent for improvements in 

 the manufacture of gutta-percha. In the first place, for the construction of a slicing 

 machine, consisting of a circular iron plate, formed with three radial slots, in which 

 knives are fixed in a similar manner to the irons of an ordinary plane or spoke- 

 shave ; the shaft which carries the plate is caused to rotate by steam or other power. 

 The lumps of gutta-percha drop against the knives, by which they are cut into 

 slices, of a degree of thickness corresponding to the projection given to the knives. 

 These slices are then soaked in a vessel of hot water till they become pliable. Instead 

 of a circular revolving cutter, a vertical cutter or chopper may be used ; curved knives 

 may be had recourse to for refractory lumps. The softened slices are next subjected 

 to the action of breakers or rollers with serrated blades, which are mounted trans- 

 versely over the tank. In front of each breaker there is a pair of fluted feeding- 

 rollers ; and the pieces of gutta-percha are passed to the rollers of the first breaker. 

 There is an inclined endless web mounted upon two rollers, the front one of which is 

 immersed in the water, and the other is situated opposite the space between the 

 feeding-rollers of the second breaker. There is a second inclined web placed before 

 the third breaker. There is also a mincing-cylinder, with radial blades working 

 partly in the water. The feeding-rollers, and the carrying-rollers of the endless webs, 

 are made to revolve in a forward direction, while the breakers, the mincing-cylinder, 

 and the agitator, are made to revolve in the opposite direction. The breakers and 

 mincing-cylinder should revolve at the rate of from 600 to 800 revolutions per minute, 

 but the feeding-rollers and endless webs need not move faster than about one-sixth of 

 that rate. Thus, the substance is reduced to fragments and washed in the water, the 

 heavy impurities falling to the bottom of the tanks, and the light purer matter 



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