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F. EXAMINATION OF WATER AND MILK,
(1) Bacteriological analysis of waters.-One thousand four hundred and eighty samples of water were tested bacteriologically. With a few exceptions all samples were from the public water supplies of the Colony, which are examined daily in a routine manner.
The analyses show that the usual high standard of purity was fully maintained.
The following table gives the sources from which the samples were obtained :-
Unfiltered raw water 112 Filtered water 114 Water from service taps throughout the Colony (filtered and chlorinated) 1118 Well waters ... Waters from other than public supplies 40 96 1480(2) Bacteriological analysis of milk.-One hundred and two samples of milk were examined at the request of private dairies.
G. MEDICO LEGAL INVESTIGATIONS.
The greater number of specimens received for investigations of a medico-legal nature were articles supposedly containing blood-stains; the remainder being clothing to be examined for seminal matter or gonococcal pus.
Thirty investigations were carried out in 1931.
During the latter part of the year the method in use for the examination of blood-stains was changed. Use was made of Takayama's solution for the production of haemochromogen crystals, and the characteristic spectrum identified microscopically. Other chemical reactions such as the guiac and benzidine tests were abandoned as being of questionable evidential value in support of the first named test which is of an absolutely specific character. A full report of the technique developed for the routine use of this test has been prepared and will shortly be published.
The technique of the precipitin test for human blood was also improved according to suggestions in Smith and Glaister's "Recent Advances in Forensic Medicine" to bring the test up to modern standards.