772 GUTTA-PERCHA 



floating. The water should bo used cold. When the gutta-percha has a fetid smell, 

 it is treated -with carbonate of soda or chloride of lime. The same apparatus may bo 

 used for purifying caoutchouc. 



Mr. Hancock combined sulphur with gutta-percha in the following manner: Ho 

 found that if a minute portion of sulphur be used along with a sulphide, the best 

 result is obtained ; the proper proportions being 6 parts of sulphide of antimony, 

 or hydrosulphide of lime, and 1 part of sulphur to 48 parts of gutta-percha. When 

 these materials have been mixed, the compound is put into a boiler and heated under 

 pressure to a temperature of from 260 to 300 Fahr., and it is to be left in this 

 state for a period varying from half an hour to two hours, according to the thickness 

 of the materials. He prefers, for effecting the union of the sulphurous constituent, 

 the following method to the masticating machine : 1. He subjects the purified gutta- 

 percha to the combined action of steam and the fumes of orpiment and sulphur mixed 

 in the proportions stated, in a metal chamber, provided with a steam-tight cover 

 secured by screw-bolts. There is also a steam-boiler connected therewith, and when 

 the heat in it is raised to about 280 Fahr., a fire is lighted beneath the pot contain- 

 ing the sulphurising materials. But the gutta-percha, &c., should be heated with the 

 steam before it is sulphurised. In from half an hour to two hours the sulphurising 

 is finished. Or, the gutta-percha may be rubbed strongly over with the sulphurous 

 mixture and then heated, either dry or with the aid of steam, or it may be coated in 

 the form of a paste. 



Another of Mr. Hancock's inventions is to expose the gutta-percha to the deutoxide of 

 azote (nitric oxide), or to chloride of zinc, concentrated and boiling hot, and then wash- 

 ing with an alkaline solution or mere water. Gutta-percha thus treated by the action of 

 the gas, as it is evolved from nitric acid and copper, iron, or zinc, becomes exceedingly 

 smooth, and of a lustre approaching to metallic ; the same effect is produced upon 

 common unsulphurised caoutchouc. Gutta-percha is thus also freed from all sticki- 

 ness ; and if sulphurised it acquires under this treatment the downy softness of velvet. 

 Chloride of zinc and nitrous gas remove the smell of vulcanised caoutchouc in a great 

 measure, especially if it be afterwards washed. 



Another invention is that of masticating gutta-percha in the proportion of 6 parts 

 with 1 of chloride of zinc ; which compound may be afterwards sulphurised. A 

 further modification consists in producing a spongy gutta-percha for stuffing sofas, &c. 

 48 parts of it moistened with oil of turpentine, coal-naphtha, bisulphide of carbon, 

 or other proper solvent ; 6 parts of hydrosulphide of lime, sulphide of antimony, or 

 other analogous sulphide ; 1 parts of carbonate of ammonia, carbonate of lime, or 

 other substance that is either volatile or capable of yielding a volatile product ; and 1 

 part of sulphur. Mr. Hancock mixes these materials together in a masticator, and 

 then subjects them to a high degree of heat, observing the same conditions which 

 are stated in the former description, except only that the heat may be pushed with 

 advantage several degrees higher, say from 260 to 300. 



Various articles are manufactured of ordinary gutta-percha, such as single and 

 double texture waterproof fabrics, boots, galoshes, belts, bandages, trowsers and other 

 straps, capes, life-preservers, tubes, knapsacks, caps, cups and other vessels of capacity, 

 hammer-cloths, cotton-spinning rollers, backs of cards for carding wool, pianoforte- 

 hammers, paper-holders, springs, trusses, &c. By taking the gutta-percha after it 

 has been sulphurised, and brushing it with a solution of resin in boiling oil (linseed?), 

 placing it in a chamber heated to from 7o to 100 Fahr., and afterwards polishing 

 it by the means usually employed by the .japanners, it acquires the lustre of japanned 

 wares. 



Mr. Hancock has also contrived a machine for cutting gutta-percha into strips or 

 riband, threads, or cord of any required shape. It consists of two grooved rollers of 

 iron or steel, mounted in a suitable framework. The grooves of each roller are semi- 

 circular, and the projecting divisions between the grooves are made with knife-edges, 

 so as to divide readily any sheet or mass of gutta-percha presented to them. The 

 under roller is flanged at both ends, and the upper roller is made to fit inside of these 

 flanges, in order to keep the cutting-edges from shifting or being damaged. To cut 

 thin sheets of gutta-percha with this machine into strips or ribands, the material is 

 passed through it in a cold state, and only the cutting-edges are brought into opera- 

 tion. To make round cord or thread by means of it, either a sheet of gutta-percha of 

 a thickness equal to the diameter of the holes formed by the grooves, and at a tem- 

 perature of 200 Fahr. (produced by supplying it from a feeding-chamber heated to 

 that degree) is passed through the machine, and the threads or cords are received in 

 a, tank of cold water, from which they are led away to be wound on reels or drums ; 

 or the gutta-percha is employed in a plastic state, and passed under a gauge before it 

 enters the machine. If it be desired to produce a cord of a semicircular form in the 

 transverse section, a plane-roller is substituted for the lower grooved-roller ; or should 



