Former methods--Former systems--Tendency to reduce number of tapping cuts and frequency of tapping--Period allowed for bark-renewal--Modern systems--Superimposed cuts--Single cuts, etc.--Tapping experiments--R.G.A. experiment--Alternate-daily _versus_ daily tapping 28 CHAPTER V TAPPING AND COLLECTING Tapping knives--Personal equation in use of knives--Choice of latex cups--Cleaning of cups--Water in cups--Premature (spontaneous) coagulation--Prevention of spontaneous coagulation--The use of anti-coagulants in the field-- Collecting pails--Payment by result--Methods for calculation of yields per coolie--Tree-scrap, oxidation of--Prevention of oxidation--Bark-shavings--Collection and storage of shavings-- Treatment of shavings--Collection of earth-scrap 38 CHAPTER VI TRANSPORT OF LATEX AND COAGULUM Percentages of "first" latex and other grades--Early collection of latex--Transport, nature of--Light railways-- Motor-lorries--Bullock-carts--Care of transport vessels--Use of an anti-coagulant during transport--Transport by coolie-- Coagulation centres (stations)--Transport of coagulum 59 PART II _FACTORY OPERATIONS_ CHAPTER VII PRELIMINARY TREATMENT OF LATEX Reception at store--Receptacles--Jars--Tanks--Necessity for close supervision--Need for utmost cleanliness--Straining of latex--Strainers--Facilitation of straining--Bulking of latex --Standardised dilution of latex--Facilities for receiving and handling latex--Reception verandahs--Receiving vessels--Types of installations 65 CHAPTER VIII COAGULATION Choice of coagulant--Strength of acid solution--Making stock solution--Quantity for use--Quantities under modern requirements--Care in mixing--Method of mixing with latex--Use of sodium bisulphite as an anti-oxidant--Quantities for use-- Formulæ--Abuse of the chemical--Residual traces in the dry rubber--Use of sodium sulphite as an anti-coagulant, quantities for use--Formulæ--Use of Formalin as anti-coagulant --Formulæ for use 74 CHAPTER IX PREPARATION OF SHEET RUBBER Pale (air-dried) sheets--Uniformity of product--Pans _versus_ tanks--The ideal tank--Modern installations--Care of tanks-- Standardised dilution of latex--Variation in dimensions and density of coagulum--Standardising instruments--Method of using--Skimming latex--Style of sheets--Standard sheets-- Rolling and marking--When to work the coagulum--Hand-rolling-- Power smooth-rolling--Marking rolls--Preparation for smoke- curing--Caution against accumulation of wet sheets--Hot-water treatment--Dripping in the open air--When to place in smoke- house 89 CHAPTER X PREPARATION OF CREPE RUBBER