11.—22

16

The receipt of samples regularly throughout the year has enabled the following table to be prepared showing the average composition of (he milk each month. The fat-determinations were made by the Leffinan-Beam method. The solids not, fat were determined by subtracting the fat from the total solids obtained by direct, weighing.

Monthly Average Composition of Unwatered Milk from Wellington and Surrounding Districts for Year 1917.

The following table, which is inserted for comparison, gives the average composition of milk supplied to the Aylesbury Dairy Company, London, as published in Dairy Chemistry, by H. I). Richmond (2nd edition). The fat-determinations were made by the Gerber method, and the solids not fat derived by calculation from the percentage of fat and the specific gravity as determined by a lactometer. To allow for the difference in seasons in the Northern and Southern Hemispheres, July in England is taken as corresponding with January in New Zealand, August with February, and so on; and the year is assumed to commence with July.

Mean Monthly Averages of Milk, 1897-1913 (Aylesbury Dairy Company).

The Wellington table exhibits greater fluctuations than Richmond shows, and the drop in quality in the early spring is much more pronounced. The Wellington average, too, is higher. Bui before satisfactory comparisons can be made the local data would need to cover a period of several years to eliminate seasonal differences. Plnnket Nurse. —Analyses of human and humanized milk are made when required, and have proved of great assistance to Plunket Nurses in their work. Other Departments. Several lubricants and boiler-waters were examined for the Railway Department, and a few samples of miscellaneous character for the Public Works and Marine Departments, and for,the Lands and Survey. A supply of pure silver nitrate was prepared for the Government Printing Office. Research. The investigation on the recovery of kauri-gum from swamp peat is being continued. An experimental plan! designed to treat 50 lb, lots has given satisfactory results, and justified the trial of the process on a commercial soale. Some preliminary results of a research on the inflammability of New Zealand coaldusts were published in pamphlet form by the Mines Department, and are being widely circulated in the coal-mining districts. Other research work has been discontinued until working-conditions become more normal.

Month. 1 Number of Samples. Fat. Solids not Fat. January February March April May June July August September October November December ■ • 169 153 142 123 161 129 124 161 117 155 170 91 3-96 4-17 4-25 4-33 4-15 4-16 3-91 3-97 3-92 3-85 3-93 4-05 8-92 8-90 9-02 9-10 9-11 9-16 9-15 9-02 8-85 9-18 9-20 9-09 Samples for year '.. 1,728 1-05 9-06 (average) (average)

! Month. Fat. Solids not Fat. Month. Fat. Solids not Fat. July August September October November December 3-63 3-75 3-84 3-92 3-97 3-90 8-77 8-76 8-85 8-94 8-96 8-96 January February March April May June 3-78 3-72 3-68 3-65 3-57 3-52 8-97 8-96 8-96 8-91 8-95 8-91 Average 3-74 8-91