FT.—34.

Chrome-plating Solution. —At the request of the Superintendent of Workshops, New Zealand Railways, a detailed examination was made of a chrome-plating solution with which considerable trouble had been experienced. From the analysis it was clear that not only was the acidity of the solution too high, but also that the ratio of chromic oxide to sulphuric acid was much above the desirable limit. After examination of the literature it was found possible to make useful recommendations for readjustment of the solution. The original cause of the trouble was in all probability due to reduction of chromic acid to chromic oxide through the use of a wooden vat as a mixing vessel. Citrus Fruits. —The investigation on grape-fruit was concluded after sufficient work had been done to show that the chemical characteristics would not give a practicable basis for time of picking the fruit. The work on the curing of lemons is now nearing completion. Cold-storage Investigations.—Preliminary investigations on the gas storage of apples were commenced during the year in the experimental cool store attached to the Laboratory, and provided data which are being used in planning the programme of work for 1938. Experiments on the cold storage of asparagus and green peas were also carried out, and yielded useful information. Further details of these experiments are given in the Fruit Cold Storage section of this Report (P- 48 )' Coal. —The whole of the chemical work on coal is now being carried out in the newly equipped special laboratory. Soils. —As in the previous year, the clay fractions of numerous soils have been separated and analysed for the Soil Survey Branch of this Department. Phormium Tenax (New Zealand Flax). —The chemical examination of samples of fibre from the standpoint of varietal differences has been continued. Other work has included chemical examination and determination of degree of damage of fibrous material produced by various methods. Ragwort.—Analyses of plant material for alkaloid content are being continued on series of samples collected at regular intervals from areas near Hamilton, the Hutt Valley, and Southland, with a view to determining the variation in toxicity in relation to locality, season, and stage of growth. Examinations have also been made of ragwort from hay and ensilage. Kauri-gum. —Samples of gum have been analysed in connection with the investigation of methods in use on the field for the recovery and cleaning of chip gum. Spray Materials (for Plant Research Bureau). —The year's work embraced the testing of various commercially available materials for certification as therapeutants. The testing covered samples of the following : Spray oil, lead arsenate, lime sulphur, hydrated lime, and nicotine sulphate. In view of arsenical spray injury which had resulted to apples in the Nelson district, an investigation was conducted to ascertain the effect of the " spreader " Agral 11, and also of certain hard waters upon the soluble-arsenic figure. The results showed that the Agral II caused no increase in soluble arsenic, but that the use of a hard water in the making-up of the arsenate spray gave rise to a dangerously high figure, in one case as high as 3-1 per cent, calculated on the dry material. In these cases it was found that the addition of hydrated lime at the concentration of 3 lb. per 100 gallons reduced the soluble arsenic to within a safe figure. Quartz Spectrograph. —During the year experience was obtained in the use of the spectrograph. This method of analysis was applied in connection with the examination of various general laboratory samples. A method was worked out for the determination of trace elements in soils. This work, however, is not to be continued at present, as the committee set up to superintend the application of spectrograph methods to agricultural problems has considered that most useful results will be obtained by examining pasture samples. At the end of the year work was begun on the estimation of trace elements in the ash of samples of milk from various healthy and unhealthy areas in North Auckland. Survey of the Thermal Region.—At the beginning of the year Dr. A. L. Day, late Director of the Geophysical Laboratory of the Carnegie Institution of Washington, visited the thermal regions of the North Island. During February and March a member of the staff was sent to Rotorua to carry out chemical work required by Dr. Day. The laboratory of the Rotorua High School was kindly made available for the work by the Director, Mr. Harwood. Under the direction of Dr. Day a survey was made of the hydrogen-sulphide content of the gases of hot springs from the main areas in the region. Simple yet sufficiently accurate methods were devised for analysing the gas-samples as soon as possible after collection, for hydrogen sulphide, other sulphur gases, and carbon dioxide. In addition, samples of water from the main hot springs were brought back to Wellington, and thorough analyses of these were made in the Dominion Laboratory. Advisory and Consulting Work. —The Director and various members of the staff were called on for reports on matters of which they have special knowledge and for service on various scientific and industrial Committees. During the year it became necessary to appoint a Librarian, which will make for a more efficient use of the technical library of the Laboratory. A number of scientific and technical papers have been published in various journals, and lectures have been delivered before scientific societies by several members of the staff. During the year arrangements were made with the Department of Agriculture for closer co-operation between the Chemical Section of that Department and the Dominion Laboratory with a view to further amalgamation of services when suitable accommodation is available. It has already been found that overlapping of work in certain directions has been obviated, and the closer contact has been to the mutual advantage of both Departments.

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