(xi) 

 Chapter XT. pac; 



The Production of Rubber from Latex 107 



Production of rubber by natural coagulation — Production on 

 a small scale illustrated — Suggestions for curing rooms — 

 Effect of Heat and Chemicals on coagulation — Smoking and 

 coagulation — The chemistry of the Amazon method — Coagula- 

 tion by chemical reagents— Acetic acid — Formic Acid— Hydro- 

 fluoric Acid — Tannic Acid — Corrosive sublimate — Amount of 

 acid to be used — Determination of completeness of coagulation 

 — A method of determining the amount of acetic acid required 

 — Advantages and disadvantages of adding chemicals to the 

 latex — Value of acids and preservatives discussed — Compo- 

 nents of coagulated rubber — Amount of proteid in mothe ■ 

 liquor and rubber — Putrefaction of rubber — Analyses of sound 

 and tacky rubber — Keeping the proteid inactive — Antiseptics, 

 drying, dilution, and washing — The removal of the proteid from 

 the latex — Formalin and sodium sulphate — Rapid coagulation 

 and removal of proteids by mechanical means — Biffen's 

 centrifugal machine — Experiments in Ceylon with the 

 Aktiebolaget Separator — Principles of mechanical separation — ■ 

 Rapid coagulation by mechanical and other means — The 

 Michie-Golledge machine : construction, action, and illustra- 

 tion — Mathieu's apparatus. 



Chapter XII. 

 Drying of Rubber 118 



General methods — Illustration showing a method of drying 

 biscuit rubber — Presence of water, putrefaction and surface 

 deposits — Chemicals and artificial heat for drying — Sugges- 

 tions by Parkin, Rurgess, and Weber — Drying in vacuum 

 chambers — Construction of vacuum chambers — High tempera- 

 tures undesireable — Dickson's drying and coagulation 

 machines— Use o ' calcium chloride — Advantages — Simple 

 rubber-drying sheds for use with calcium chloride — Disadvan- 

 tages — Experiments in Ceylon, and softening of rubber. 



Charter XIII 



Physical and Chemical Properties of Rubber 122 



Analyses of Para rubber from Ceylon, Bukit Rajah Co., F.M. 

 S., Penang, Straits, and Gold Coast — Market value of the 

 samples — Para and African rubber analyses compared — Resins 

 in Para and Castilloa rubber — Resins in rubber from parts of the 

 same tree — Resins in rubber from Para trees of different age- — 

 Para compared with other rubbers — Chemical composition and 

 value of Ceara, Castilloa, Ficus. Landolphia, Urceola, and 

 Rhynocodia rubber — Extraction of resins from Rubber by 

 manufacturers and growers — Albuminoids and cause of putre- 

 faction — Removal by mechanical and chemical processes- 

 Ash impurities and ingredients present in Para, Ceara, and 

 African rubbers — The insoluble constituent in rubber — 

 Properties of indiarubber, reaction with alkalies, halogens, and 

 acids — Absorption of water — Sulphur reaction — Action of 

 heat on indiarubber. 



