A Practical Manual On Sea Water Distillation
With A Description Of The Necessary Machinery For The Process

BOARD OF TRADE RULES. 159 grease cocks. The presence of zinc in such boilers is con- sidered objectionable. 38. A relief valve is required on the distiller casing for the escape of the circulation water, if necessary ; and if the casings of the apparatus cannot stand boiler pressure, there should be a safety valve fitted between the steam pipe and the apparatus. 39. A list of tools and materials is included in the rules, the principal items of which are as follows :— Stoking tools ) (that is, for a donkey boiler, if Set of fire bars ) supplied). Scaling tools. Spanners. A double charge of animal charcoal. Salinometers (two made of glass) and brine pot for use therewith. 40. Besides the Board of Trade Rules there are various other regulations applicable to boilers, which would also apply to evaporators working under pressure. These regulations principally are those issued by the (1) Ad- miralty, (2) Lloyds, and (3) Bureau Veritas. These are also to be found in Seaton & Rounthwaite's Pocket-Book.