473 
ingenious. A long strip is cut from a thin sheet of dough, and this 
is cut into lengths of a few inches, not by simple cross diversions 
but by oblique cuts. These lozenge shaped strips are then wrapped 
round a smooth circular rod and the sloping ends pressed together. 
A band is thus formed round the rod and the line of junction of 
the two original ends of the strip passes obliquely across the band. 
The workman, or rather workwoman, then rolls up into a ring 
v with her fingers this flat band, still upon the rod, and by rolling it 
backwards and forwards upon the rod makes a smooth ring of it. 
The object of cutting the strip with oblique ends— or “ on the 
cross ” — is now evident, because the line of original junction 
which naturally would would be the weakest place in the ring, is 
spread out over a considerable length of the ring and it is every- 
where w T rapped round and supported by whole and unjointed 
ayers of rubber, becoming thus nowhere more than a small portion 
of any part of the cross section of the ring. Screw stoppers for 
bottles are mechanically stamped out of a dough which contains 
a high proportion of sulphur and which gives a hard product on 
vulcanisation, the dough is stamped in two stages, first a simple 
cylindrical rod is made and cut lengths of this are then fed into a 
powerful press which produces the final shape. For large and 
awkwardly shaped goods, such as the outer covers for pneumatic 
tyres, specially devised iron moulds to completely encase the trye 
and exert pressure upon it during vulcanisation are prepared. 
These moulds are in several portions and have to be fitted round 
each tyre separately and the portions keyed into contact. Flexible 
rubber tubbing where the rubber is solid and not, as in hose piping 
associated with canvas, is squirted out of a machine provided with 
compound nozzles, the apertures in which are ring-shaped. The 
$ rubber dough is ejected through this annular orifice as a hollow 
tube which only requires heat vulcanisation for completion. 
A detailed account of the mechanical difficulties encountered 
in this part of the work, and the way they are surmounted, would 
be of little use and certainly tedious ; the principal underlying all 
processes is the same — namely, moulding plastic dough and.then 
reproducing the elasticity and tenacity of the rubber goods by 
heat and vulcanisation. 
29. Rubber goods that are “ built up ” fall naturally into two 
classes, according to their being pure dough or compounded with 
other materials, as in the case of outer covers for tyres, hose piping, 
rubber belting, etc. The general mode of treatment is the same in 
all cases, and it is a mixture of joinery and tailoring. The dough 
is soft and plastic and so can be rolled to any thickness, cut to any 
shape, and applied to the goods in any manner. The dough con- 
tains raw rubber and therefore is adhesive, cut edges of it can be 
pressed into contact and that with the greatest ease if the edges or 
surfaces are previously moistened with any rubber solvent. The 
tools necessary for use in this work are consequently of the simplest 
— a keen knife or stamps for cutting shapes, a squeejee for pressing 
surfaces into contact, and a pot of benzine with a piece of cloth as 
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