Early Studies of Radioactivity
What must be considered as one of the first studies of the applications of radioactivity was also made by Farr and Florance in 1909. They examined Christchurch artesian waters for radium emanation and stated that “as this gas has properties of a remarkable and energetic character, it occurred to us to endeavour to ascertain whether any, and if so, what, effects on animal life could possibly be ascribed to it”. They appeared to find some correlation between radioactivity of the waters and a disease called blue swelling amongst young trout in the yolk-sac stage. In a later paper, 1910, C. C. Farr and D. B. MacLeod stated that it was practically impossible to decide between a defect of oxygen and an excess of radium emanation as the cause of the increased mortality both in the egg and in the yolk-sac stage of the trout.
Using the same standard radium solution prepared by Rutherford, J. S. Maclaurin, Dominion Analyst from 1900 to 1930, discussed in the forty-fifth annual report of the Dominion Laboratory, 1911, work by himself and C. M. Wright on the radioactivity of the thermal waters of Rotorua, Taupo, and Te Aroha. Radium emanation given off from radium was boiled out of water, dried, and passed into an electroscope. These waters contained very much less than 10-1 2 g per c.c. while the radium content of sinters in the thermal areas were reported as containing nearly 10-1 2 g radium to a gram of sinter.
Ten years later, in 1921, work on the radioactivity of thermal waters was extended by F. J. T. Grigg, Dominion Analyst (1947–60), and M. N. Rodgers, then doing an M.Sc. thesis at Victoria University of Wellington. This work was stimulated likewise by the possible beneficial effects of ionising radiation to health. In 1922 Grigg and W. J. Phillipps, of the Dominion Museum, were able to show that it was not radium emanation but lack of dissolved oxygen that caused mortality in trout young. Farr of Canterbury College still kept up his interest in radioactivity for in 1927 he suggested to M. N. Rodgers a possible correlation between radioactivity and goitre incidence. The high radium emanation of Christchurch artesian waters made such a study possible, but no correlation of radioactivity with goitre incidence could be found. A correlation of goitre with lack of iodine in water was shown also in this paper.
R. R. D. Milligan, of Christchurch, who had been participating in the experiments of Farr, Florance, and Rodgers, decided to test whether there was any causation of goitre production through radium emanation. He injected six rabbits with large doses of radium emanation (radon). The rabbits thrived, showed no abnormal symptoms, and it did not appear that radon could be an important factor in the appearance of goitre, at least among rabbits.
It was another 15 years before New Zealand scientists concerned themselves in the applications of nuclear science, so ably championed by Rutherford up to his death in 1937. This may have been due to the detection of nuclear phenomena passing from the simple electroscope to more expensive nuclear machines that were available only in a few advanced research laboratories overseas.