113 



The synthetic rosins may be sokible or insoluble in alcohol depending 

 on the conditions of manufacture and show a great variety of cliemical 

 and physical properties. Their composition is complex (Lebach, 

 J.S.G.I., 32, 559, 1913). The preliminary substance is a phenol 

 alcohol, CeH, (OH) CHOH. 



Bakehte discovered by Baekeland, consists of soluble and insoluble 

 forms. On stovmg alcohol-soluble Bakehte at 140°-170° it passes 

 to a hard insoluble layer or lacquer or to a solid of high chemical 

 and mechanical resistance (Bakelite C, Resite). 



Resite has been considered to be. derived from polymerisation 

 products of CH, : <— > = (Wohl, Ber., 45, 2046, 1912). 



The advantages of further study of such synthetic organic coUoids 

 seem to invite mquiry. Viscosity, gelation, relaxation effects, and 

 dielectric properties are of importance, and, with the exception of the 

 latter, await investigation. 



There remains one important class of varnishes, viz., the black 

 japans and black varnishes \vith carbon black as base. 



In general, the pitch base blacks ought to show similar behaviour 

 to the resin mixings or to resin mixings containing no oil with 

 allowance for the nature of the pitch (asphaltum or resm or stearine). 



The knowledge of their properties is in the hands of the craftsmen 

 and owing to the complexity of the mixings is of the nature of a trade 

 secret. 



Those on a carbon black base involve the knowledge of the properties 

 of carbon black in non-aqueous media. The suspensoid black in 

 a high degree of fineness adsorbing the continuous medium is assisted 

 by an emulsif3dng colloid forming a membrane around the particle 

 of black. 



The results obtained from attempts to produce liquid fuel from 

 petroleum and coal dust are industrially appUcable m this case, but 

 the presence of resin and oU gives a more favourable medium for 

 holding the carbon black in suspension. 



From the brief summary of a very scanty literature it wiU bo 

 evident that although the main properties are conditioned by the 

 chemical composition of the components, nevertheless the properties 

 which decide betv\een a high and low class of article or bet\\een 

 suitability or unfitness are rather to be looked for in a comparison 

 of relationship of phases and in changes of surface energy and 

 adsorption. 



The author desires to express his thanks to Mr. P. J. Fa^', M.A. 

 for help in the selection and arrangement of the material for this 

 report. 



CLAYS AND CLAY PRODUCTS. 



B7J A. B. Searle, Consulting Chemist, Sheffield. 



The details of the structure of clays and clay products are to a 

 large extent unl^noAvn. This is due to the variety of the mateiials 

 commonly known as days, to the complexity of the reactions which 

 take place \Ahcn the clays are moistened, dried, and heated, and to 

 the extreme difficulty in studying the products of the reactions. 



X Hi54 H 



