H.—34,

Phormium Tenax. Chemical Examination. —Several varieties have been examined chemically with a view to determining differences in fibre quality. Differences have been found to occur, and the work is being extended to other varieties. Processes for Treatment.—Reports were made as follows : (1) The explosion process for stripping. The fibre produced was of less value than ordinary unscutched stripper fibre for textile purposes, and very little cheaper. It was not suitable for the manufacture of finer grades of paper. (2) Process for softening fibre by bacterial retting for a short period. The claim that the product produced a softer and finer fibre, suitable for spinning fine yarns, was not substantiated. (3) Tail stripper. Spinning tests were made on fibre produced by this process. The strength had not been impaired and the losses in processing were no greater than those experienced with ordinary tail-clipped fibre. The yarn produced created a favourable impression. Ragwort. Samples collected at monthly intervals during one year from areas near Hamilton have been analysed for alkaloid content. Samples collected from the Hutt Valley over a period of eighteen months have been similarly examined. Certain variations have been observed and the work is being continued. Curing of Lemons. The laboratory work on curing of lemons was brought to a conclusion during the year, and a full report is being published in the New Zealand Journal of Science and Technology. The best results were obtained by storage in a slow current of air at a temperature of 70° F. and a relative humidity of 90 per cent, for a period of from five to six weeks. Coal-gas to the extent of Ol per cent., equivalent to ethylene 1 part in 30,000, was introduced into the air stream for the first three weeks. Fruit so treated had shrunk somewhat, giving greater resilience, the skin was reduced considerably in thickness and was tougher, the colour was improved, and the juice content had increased in quantity and was of more mature flavour compared with fruit not so treated. To complete the work a large-scale storage trial under the conditions recommended should be made. Gas-storage. Work has been continued on the gas-storage of apples of the Washington and Ballarat varieties. A considerable amount of information has been obtained on the behaviour of these apples in atmospheres containing carbon dioxide. It appears that some improvement in quality of fruit and in length of storage life is obtained by storing the Ballarats at 39° F. in an atmosphere containing 2-5 per cent, to 5 per cent, of carbon dioxide and 18-5 per cent, of oxygen, and the Washingtons in 5 per cent, of carbon dioxide with 16 per cent, of oxygen. Under most of the other conditions tried various physiological-disorders developed. For fuller details reference should be made to the section " Fruit Cold Storage Committee " (see page 73). Spraying-materials. Analyses of spray materials for the Plant Research Bureau have been continued, samples of lead arsenate, lime-sulphur, nicotine sulphate, and spray oil being tested for certification. Over one hundred samples of New-Zealand-grown Pyrethrum flowers were analysed for their content of Pyrethrins 1 and 2, the method used being that of Gnadinger and Corl. The amounts of Pyrethrins found varied from 0-7 per cent, to 1-9 per cent. A series of the commercial spreaders on the market was examined with a view to ascertaining their approximate composition. Most proved to be of the casein type, whilst the remainder were sulphite lye or sulphonated organic products. • Paints. A very large quantity of paint is used each year on Government-owned buildings by the Post and Telegraph and Public Works Departments. The Property Divisions of the Public Trust Office and the State Advances Corporation also require large aggregate amounts for use on residential and other buildings under their care. With the setting-up of the Housing Construction Department the State purchases of paint were further increased. Work in previous years had demonstrated the value of analysis in checking up the quality of supplies, and there was a decided increase in the number of samples submitted during the year under review. Each paint is examined for composition and proportion of pigment, and nature and proportion of oils and thinners, which must be in accord with specifications issued by the Department concerned. As a check, the weight per gallon is also determined. Both pigment and oils used must comply with the respective British standard specifications. Several samples of paint scrapings were also examined with a view to ascertaining the cause of paint failure in specific cases. A Paint Investigation Committee, composed of representatives of the various interested Departments and of the Laboratory, has been set up to arrange for large-scale trials, by which it is hoped to correlate the composition of paint, and also varying painting procedure, with protection of the underlying material and durability.

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