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with the tobacco-kiln work. The design proved promising and a number of further units Were constructed at the Dominion Physical Laboratory. These were calibrated and have been found very satisfactory for measurement. of air-velocity between 15 ft. and 200 ft. per minute. A Fuel Technologist was appointed to the staff in November to initiate the projected work on industrial fuel efficiency. Until such time as the necessary staff can be obtained, the work will be largely confined to the testing of steam-raising equipment, furnaces, &c. Equipment has been obtained for the measurement of C0 2 , temperature, steam flow, &c. An officer of the section collaborated with the Radio Development Laboratory in developing methods for measuring humidity at various heights in the atmosphere. Lack of staff has prevented progress on an investigation of processes for the -commercial preparation of New Zealand bentonite. A commencement has, however, been made on the design of pilot plant for carrying out this work. The section has been asked to design an experimental plant for the research on antibiotics to be carried out at the Plant Chemistry Laboratory, and the necessary work has been commenced. As in previous years, the section has been called upon to do a certain amount of design and advisory work for the other sections of the Laboratory and has also been consulted on industrial problems. Metals and Corrosion While the stoppage of munitions-production following the cessation of hostilities considerably altered the character of the work undertaken in this section, more .attention being given to problems affecting industry, the volume of work has been maintained. Chemical analyses were made of a variety of metals and alloys either to establish their nature, to test their compliance with specification, or to assist in ascertaining the cause of metallurgical failures. The samples examined included ninety steels, twenty zinc alloys, seventeen brasses, twelve bronzes, sixteen lead alloys, solders, and type metals, besides a number of aluminium alloys, ferro-alloys, magnet alloys, fluxes, and other metallurgical products. A great deal of analytical work was also required in the investigation of corrosion problems referred to below. A number of commercial ;zinc and cadmium plating solutions were analysed for metal content, and chemical methods were used for estimating the thickness of electroplated coatings. In the analytical work considerable assistance was received from the Physical Chemistry Section, particularly in the determination of minor constituents and in the rapid qualitative determination of compositions. Advice was given in a number of cases on the suitability of metals for use under specific conditions. Mechanical failures in machinery were found to be due to the use of steel and wrought iron of low fatigue strength in locations subject to severe vibration. Damage to an aluminium-alloy cylinder head was shown to be due to overheating. Soldering difficulties were traced to solder of unsuitable composition. Advice was given on problems connected with the tinning of cast iron and of copper. The steady increase in the number of corrosion problems submitted to the Laboratory in recent years emphasizes the serious economic loss that is continually being caused by the corrosive wastage of metals and the necessity for more attention being given to this matter. A number of lead sheaths from telephone cables were examined for the Post and Telegraph Department. In most cases the evidence indicated that the corrosion was ■due to stray electrical currents. Corrosion of bearings was found to be due to sulphurcontaining additives in lubricating-oil. The pitting of tinned copper sheet was believed to have resulted from electrochemical action between the copper and the heavy copper-tin-alloy layer that had been formed as a result of overheating the sheet. Corrosion of •silver contacts in automatic railway signalling gear was traced to sulphur derived from plastic insulating-material.

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