CAOUTCHOUC 699 



like that of the slide-rest of a lathe. In cutting caoutchouc by knives of every form, 

 it is essential that either the blade or the incision be constantly moistened with water; 

 for otherwise the tool would immediately stick fast. As the above straight vibrating 

 knife slants obliquely downwards, the sheet which it cuts off spontaneously turns up 

 over the blade in proportion as it is detached from the bottom mass of the cake. The 

 thicker slices are afterwards cut by hand, with a wetted knife, into small parallel- 

 epipeds for the stationer, the sections being guided rectangularly by saw lines in a 

 wooden frame. Slices may be cut off to almost any desired degree of thickness, by 

 means of an adjusting screw a mechanism that acts against a board which supports 

 the bottom of the cake, and raises it by an aliquot part of an inch, the cutting blade 

 being caused to vibrate always in the same horizontal plane. These thin slices con- 

 stitute what is called sheet caoutchouc, and they serve tolerably for making tubes for 

 pneumatic apparatus, and sheaths of every kind ; since, if their two edges be cut 

 obliquely with clean scissors, they may be made to coalesce, by gentle pressure, so in- 

 timately, that the line of junction cannot be discovered either by the eye, or by inflation 

 of a bag or tube thus formed. 



The mode of recomposing the cuttings, shreds, and coarse lumps of caoutchouc into 

 a homogeneous elastic cake, specified by Mr. Nickels, for his patent, sealed October 24, 

 1836, is not essentially different from that above described. The cylinders of his mill 

 are more capacious, are open at the sides like a cage, and do not require the washing 

 apparatus, as the caoutchouc has been cleansed by previous lamination and rinsing. 

 He completes the kneading operation, in this open cylinder, within the space of about 

 two hours, and afterwards squeezes the large ball so formed into the cheese-form, in a 

 mould subjected to the action of an hydraulic press. As he succeeds perfectly in 

 making compact cakes in this way, his caoutchouc must differ somewhat in its physical 

 constitution from that recomposed by Mr. Sievier's process. He uses a press of the 

 power of 70 tons ; such pressure, however, must not be applied suddenly, but pro- 

 gressively, at intervals of two or three minutes between each stroke ; and when the 

 pressing is complete, the caoutchouc is allowed to remain under pressure till it is cold, 

 when he thrusts it out of the mould entirely, or, placing his mould in the slide-rest 

 mechanism, he gradually raises the caoutchouc out of it, while the vibrating knife 

 cuts it into slices in the manner already described. The elegant machine by which these 

 sheets are now so easily and accurately sliced, was originally contrived and constructed 

 by Mr. Beale, engineer, Church-lane, Whitechapel. 



II. FILATTJBE OP CAOUTCHOUC FOB MAKING ELASTIC FABBICS 



The following particulars may be deemed as belonging to the history of the manu- 

 facture of threads of native rubber, the cured, or vulcanised, or mineralised rubber 

 having quite superseded the modes of preparing threads from native bottle caoutchouc. 



Messrs. Eattier and Guibal mounted in their factory at St. Deny's, Dr. Ure says, in 

 the year 1826 or 1827, a machine for cutting a disc of caoutchouc into a continuous 

 fillet spirally, from its circumference towards its centre. This flat disc was made by 

 pressing the bottom part of a bottle of India-rubber in an iron mould. A machine 

 on the same principle was made the subject of a patent by Mr. Joshua Proctor West- 

 head, of Manchester, in February 1846; and, being constructed with the well-known 

 precision of Manchester workmanship, it has been found to act perfectly well in 

 cutting a disc of caoutchouc, from the circumference towards the centre spirally, into 

 one continuous length of tape. For the service of this machine, the bottom of a bottle 

 of India-rubber of good quality being selected, is cut off and flattened by heat and 

 pressure into nearly a round cake of uniform thickness. The cake is made fast at its 

 centre by a screw nut and washer to the end of a horizontal shaft, which may be made 

 to revolve with any desired velocity by means of appropriate pullies and bands, at the 

 same time that the edge of the disc of caoutchouc is acted on by a circular knife of 

 cast steel, made to revolve 3,000 times per minute, in a plane at right angles to that 

 of the disc, and to advance upon its axis progressively, so as to pare off a continuous 

 uniform tape or fillet from the circumference of the cake. During this cutting opera- 

 tion, the knife and caoutchouc are kept constantly moist with a slender stream of 

 water. A succession of threads of any desired fineness is afterwards cut out of this 

 fillet, by drawing it in a moist state through a guide slit, against the sharp edge of a 

 revolving steel disc. This operation is dexterously performed by the hands of young 

 girls. MM. Kattier and Guibal employed, at the above-mentioned period, a mechanism 

 consisting of a series of circular steel knives, fixed parallel to each other at minute 

 distances, regulated by interposed washers upon a revolving shaft ; which series of 

 knives acted against another similar series, placed upon a parallel adjoining shaft, 



