47i 
COLD CURE. 
24. Although pure sulphur does not combine with india- 
rubber at a temparature below 270° F., yet a compound of sulphur 
with chlorine — namely, mono-chloride of sulphur — does react on 
rubber, and the sulphur is transferred from the chloride of sulphur 
to the rubber, and vulcanisation takes place rapidly and complete- 
ly at ordinary temperatures. This action with pure chloride of 
sulphur is too violent; this agent is therefore diluted and a solu- 
tion of 2-3% chloride of sulphur in carbon bisulphide is used. The 
article to be vulcanised is immersed in this solution, and left for a 
few minutes, the time- varying with the thickness of the rubber ; it 
is removed, drained, and finally washed with water. The cham- 
ber in which this dipping takes place must be specially arranged 
to prevent the fumes of the solution, which are poisonous and 
corrosive, coming into contact with the workmen. This cold cure 
is used for goods which from their nature would be damaged by 
exposure to the temperature required for heat vulcanisation, and 
also for goods in which the presence of uncombined or free sulphur 
is objectionable, or which have been made by accumulation of rub- 
ber by dipping in rubber solution, as is the case with teats for 
infants’ bottles, and in some surgical goods. 
Solution Making. 
25. In dissolving rubber for making solution or pastes for 
spreading on fabrics, benzole is the solvent generally used. The 
process is simple, the washed dry rubber is soaked in the solvent 
and then ground up with the solvent in enclosed boxes, in which 
are several pairs of small rollers which thoroughly mix the rubber 
and solvent, and according to the relative amounts of rubber and 
solvent produce a solution free from lumps. If a solution of plan- 
tation rubber be made by shaking rubber and benzole in a glass 
bottle a turbid instead of a transparent solution results. This is 
due to a small quantity of a resinous body which is always nor- 
mally present in all Para rubber, and which is not soluble in ben- 
zole. The effect of the mechanical rolling in solution making in 
the factory, is ao largely break up and incorporate the flakes 
of this resin and render the whole homogeneous and transparent. 
Thorough mastication of the rubber also tends to produce this same 
result, and rubber after complete mastication is far more inclined 
to dissolve to a clear solution in rubber solvents than simple sheet, 
biscuit, or crepe rubber. This point I mention because the solu- 
tion of samples of rubber in solvents is one test of the purity of 
rubber, and the presence of this insoluble resin, which appears 
large in bulk, but which is in' reality only a small fraction of a per 
cent., is apt to prove disconcerting to the person making the test. 
Final Mechanical Processes. 
26. The detailed mechanical manufacture of the actual rubber 
goods of commerce can only have an indirect interest to the rubber 
grower ; but though indirect, it is, I consider, sufficiently great to 
justify the inclusion of an account of some of these processes in 
Hus 
