Document Z4ywvrvpByrQ1wkQeOgg0GVdY

</ u i \boha70hy vn nioss to delays incident in the installation of special pieces of equipment, work on many of these subjects did not get under way until relatively late in the year. Asbestos D. W'oiocbow After several meetings with representatives of the Canadian producers, at which the technical problems of the industry were discussed, it was decided to undertake work wiih the object of. (a) standardizing the present method of testing asbestos grades, fb) developing new methods of testing such as will take into account all the various properties of the fibre which are of significance in manufacture, (c) developing new uses for asbestos, especially for the shorter fibred grades. Work was started in November, 1930. The producing mills and a num ber of asbestos manufacturing plants were first visited and data were secured on the results of testing the various grades of fibre in the Quebec Standard Testing Machine and also on Ro-lap screens. Work has also been done on the influence of drying, on testing, on the determination of the moisture and water-soluble content in asbestos, and on the absorption of water by asbestos. A new method of testing, based on the apparent density of the.fibre, is being studied. Washing tests have been made. Asbestos of foreign origin has also been examined for compara tive purposes. Some studies have been made on the properties of asbestos of various grades bonded with Portland cement and other binders, and this work is leading to the production of some new asbestos cement and moulded com positions which, it is hoped, will prove to be of commercial value. The activities of the Associate Committee on Asbestos are briefly described under that heading, beginning on page 34 of this report. Plastic Magnesia A. F. Goi, N. P. Put, C. TV. Davis Laboratory work on behalf of the magnesite companies has been directed towards improvement of the properties and methods of utilization of the plastic magnesia and the development of new uses. A study'was made of the effect of the factors of time and temperature in calcination subsequent to the carbonate decomposition. It was found that the physical properties of a plastic magnesia could be modified by heat treat ment to give the desired setting time; high water resistance and diminished linear change. It was possiblorto take advantage of these results in the com mercial production of plastic magnesia in spite of the limiting temperature below which Canadian magnesian rock must be calcined to avoid production of free lime. This was accomplished by close sizing of kiln feed, careful control of the burning period and improved technique in temperature measure ment aDd control. Further laboratory experimentation on the expansion and contraction of plastic magnesia cements, together with observations of existing installa tions, had indicated that climatic conditions in eastern Canada are a major factor in its ct reported as sr.:i: under the i: * v A large c-l: of develop::.; c: changes. 2' lz; of aggregate si:t safely stair." c: position ficcr; J. resiliency ai: tt: are now in nr let An invtsrigat satisfactory rag: mechanical y::?e: scale. Other ir.::r.e.{ tion trials ir. :he floor and waii i.itto be equal t: `.lieestablishment :f : templated. Efforts art :e: power and fir;-:re building proc.rts been obtained With the r::t 1931, some acc.-.lor. preliminary quriita droxide of mar.esi made of the c::d.' solutions of re.:::', factory way c:::l. Weed set:': si: represent in th* ::: head of the lakt; a separated at these t tons and in the y;:: thirds of these s:r:-i or no monetary -;! National Restir;; Of the vnr'.r :s manufacture of been dcvc-lc-pni :r. ;