702 CAOUTCHOUC 



In tho manufacture of elastic fabrics, the riband looms at Holloway displayed to 

 great advantage tho mechanical genius of tho patentee, Mr. Sievier. Their produc- 

 tive powers may be inferred from tho following statement: '5,000 yards of 1-inch 

 braces are woven weekly in one 18-riband loom, whereby the female operative, who 

 has nothing to do but watch its automatic movements, earns 10s. a-week : 3,000 yards 

 of 2-inch braces are woven upon a similar loom in tho same time.' But one of 

 Mr. Sievier's most curious patent inventions is that of producing, by the shrinking of 

 the caoutchouc threads in the foundation or warp of the stuff, the appearance of raised 

 figures, closely resembling coach-lace, in the weft. Thus, by a simple physical operation, 

 there is produced, at an expense of one penny, an effect which could not be effected by 

 mechanical means for less than one shilling. This manufacture is not now carried on 

 in that locality. 



HE. OP THE WATEB-PROOF DOUBLE FABRICS. 



In 1837, Mr. Hancock obtained a patent to produce waterproof cloth with greatly 

 reduced quantities of dissolved caoutchouc, and in some cases without any solvent at 

 all. The masticated rubber, rolled into sheets, was moistened on both 'sides with 

 a solvent and rolled up. The following day these were submitted to rollers of different 

 speeds, and the whole became a plastic mass. Instead of a wooden plank, as the bed 

 of the machine, a revolving iron cylinder was used, kept hot by steam or water, and 

 the coated cloth passed over flat iron chambers, heated the same way, to evaporate 

 the small quantity of solvent. Masticated rubber has been spread without any solvent 

 by these machines ; but the spreading is best effected by the rubber being in some 

 degree softened by the addition of small quantities of the solvent. 



Sheets of rubber have been prepared by saturating tho cloth with gum, starch, glue, 

 &c., then rubber dough was placed on this smoothed surface ; sufficient coatings of 

 the rubber were spread to make up the desired thickness, the cloth was immersed in 

 warm water to dissolve the gum, when the sheet of rubber came off with ease, and the 

 plastic, or dough state, was the precursor of vulcanisation experiments and success. 



The clamminess of caoutchouc is removed by Mr. Hancock in the following manner: 

 10 Ibs. of it are rolled out into thin sheets between iron cylinders, and at the same 

 time 20 Ibs. of French-chalk (silicate of magnesia) are sifted on and incorporated 

 with it, by means of the usual kneading apparatus. When very thin films are 

 required (like sheets of paper), the caoutchouc, made plastic with a little naphtha, is 

 spread upon cloth previously saturated with size, and when dry is stripped off. 

 Mixtures of caoutchouc so softened may be made with asphalt, with pigments of various 

 kinds, and with plumbago, sulphur, &c. 



The first form of bags or pillows, or ordinary air-cushions, is well known, and was 

 manufactured by C. Macintosh and Co. as early as 1825 and 1826; when pressure 

 is applied they yield for the instant to the compressing "body, and then become rigid, 

 and the whole strain is borne by the inelastic material of the bag. Mr. T. Hancock 

 once tried an ordinary pillow between boards in a hydraulic press, and ho records 

 that it bore a pressure of 7 tons before it burst. To remedy the evils of this 

 form an ingenious arrangement was made of inserting slips of India-rubber into 

 tho fabric, so that it expanded in every direction. This yielding of tho case, and 

 division into strengthened partitions, enabled seats, beds, and other applications to 

 be made. 



The gas-bags now so commonly used appear, by Mr. Hancock's statement, to have 

 been made for experimental purposes in the year 1826; and in May 1826, at the 

 suggestion and for the use of Lieut. Drummond, to be employed in the Trigono- 

 metrical Survey of these islands, with the oxy-hydrogen jets of gas on balls of lime. 



They were made strong and of rough materials fustian made air-proof with thin 

 sheet rubber. Mr. Hancock, to try whether the rubber was absolutely impervious to 

 water, had a bag made and weighed it from time to time during 30 years ; the decrease 

 of weight is shown : 



Ib. oz. drch. 



Oct. 21, 1826 weight 114 



Oct. 25, 1827 , 112 



Oct. 2, 1835 



Nov. 1844 



Oct. 1849 



Feb. 1851 



May 1854 



1 

 14 12 

 13 4 

 078 

 3 14 



In 1856 it was cut open and weighed . .0312 



It was quite dry. Thus 12 oz. of water had evaporated or escaped in a quarter of a 

 century, and 13 oz. 8 dr. in 30 years of observation. 



