MANIPULATION. 161 



ence to both of these methods, as in the use of India rubber for 

 cementing, it is necessary to observe the directions before given, 

 page , and to see that the gum is used before it ferments or 

 becomes sour. 



MANIPULATION. 



After the gum is rolled into sheets, or spread upon cloths, or 

 blended with fibrous substances and made into the laminated 

 fabrics, the manipulation of the manufacture is so very simple 

 and easy, that much need not be said on the subject. 



When the fabrics are taken from the spreading machine, they 

 are in a state as adhesive as that of the native gum, and it 

 requires great care and skill to handle the goods in working, to 

 prevent the surfaces adhering together and becoming one solid 

 mass, which cannot be separated. In order to prevent this, the 

 sheets are rolled up in cloth, or dusted with flour. The articles 

 which it is desired to manufacture being cut out, the seams are 

 washed clean from the flour, and the parts being brought in 

 contact, and pressed with the fingers or a small hand roller 

 about the size of a dollar, they are firmly united, and the article 

 is ready for vulcanizing. Some articles are cemented, or made 

 up by machinery, as in the case of shirred goods and improved 

 air work. Articles which are to be formed into various shapes, 

 made of the compound, without cloth, require to be put on forms, 

 or lasts, or into moulds, or to be otherwise supported, in order 

 to prevent a change of shape when the gum becomes soft in the 

 oven. The working of all the articles, whether of the gum or 

 the fabrics, of whatever shape or form, admits of great cheapness 

 and dispatch, as has been stated with some particulars, page 

 Some peculiarities in the working of the different fabrics and 

 wares are remarked upon in the description of them, under 

 the head of Fabrics. 



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