INDIA-RUBBER LABORATORY PRACTICE - PREFACE - IN these pages an attempt is made to give the specialized practical information-at least in broad outlines-required by chemists of sound general training who may be called upon, in whatever capacity, to deal with india-rubber and its accessories. The botany and theoretical chemistry of india-rubber, with which it has become almost common form to embellish all books on the subject, are here barely mentioned. More reluctantly, two important branches of science applied to india-rubber, viz., the production of the raw material and the mechanical testing of manufactured rubber, have also been passed over, mainly because they are as yet in the mere beginnings of giving rise to systematic laboratory practice. There are two kinds of analytical text-book, the more . or less exhaustive and less or more critical compilation from literature, and the strictly practical and inevitably somewhat biassed manual based on personal experience. Which of the two is the more valuable is a debatable point and indeed they are rather complements than competitors. The present work, at any rate, claims in all modesty to belong to the second category, no analytical method being descril edin it -1iicll h as not been practised and found sntisfnctoi-y by the 111thor, ill the course of tlre last ten -ears. If tllus some infoi n rtioonf - due to the rubber chemist fili1. j to find place, it inay be hoped, 011 the other hand, that the n inimunr of space is tilke11 1111 by matter 11-hich time ancl experiment hm e pl ove otiose. Losuos, Dcc. 1913. CONTENTS - CHAPTEII I PAGE CI1I7DE ASD V- SIiED RCBl3ER . . . . . . . . 1 Wild ancl Plarltation Rnljbers. Sampling. Analysis. Significance sf Analytical Data. CHAPTER I1 a r a c a I s i u , y ATD RPPARATTS . . . . . . . 1S ITashing Xills. Determinatio l of Washing Loss. RIixiiig Rlills. Centrifuges. Laboratory Apparatus. CHAPTER I11 RL713BER DILIESTS . . . . . . . . . . 37 Factice. Reclaim. Eitumen ancl Pitch. Resins. CHAPTER IV SOLI11 COJIPOUSDIS 4 MATERIATJS . . Accelerators. Fillers. ligments. CHAPTER TT RIISCELL-kSE0CSACIC ESSORIES . . . . . . . . 8s Solvents. Sulphur ailcl Sulphur Cliloride. Oils and Taxes. Fabrics. I I 1 - l l O c I I . . . . 110 I strnctio is. Co iil iiict S l nlphul.. Li1vnlcnnized C ootls. Solutions. E1 oilit. e. Reclitill1 ill 12ul l er ootls. INDIA-RUBBER LABORATORY PRACTICE CHAPTER I CRUDE AND WASHED RUBBER THE raw material which forms the basis of the-rubber industry is a gum imported from the tropical regions of Asia, Africa, and America. Most of it is obtained primarily in the form of an aqueous emulsion or latex secreted by the bark of certain trees and creepers from this latex the rubber is won, as a tenacious, springy, self-adhesive mass, by methods of coagulation which vary somewhat widely with botanical origin, local custom, and other factors. In a few instances notably that of Guayule, a Mexican sort, the rubber as such is directly extracted from roots and other plant parts. Rather more than half the total production of rubber originates from plants growing wild, and this wild rubber, which is almost the only kind produced in America and Africa, is always more or less moist, dirty, and inhomogeneous. The imports from Asia nowadays consist for the greater part of clean dry rubbers prepared by rational methods on plantations organized and managed by Europeans in Ceylon, the Malay Peninsula, the Malay Archipelago - islands, and India...