March 7, 1918' 



NATURE 



this district showing their lcx:ation, but at a later 

 date the well-known hot springs of Banff, at the 

 eastern gate of the Canadian Pacific railway across 

 the Rockies, were also included and found to be 

 the most radio-active of those yet examined in 

 Canada. Very full and clear descriptions and 

 plates of the method of testing and apparatus em- 

 ployed are given, together with plates of twenty- 

 one of the springs. The unit of measurement 

 adopted is the scientific one, either lo-^^ curie of 

 emanation, or lO'^^ gram of radium per litre of 

 water, respectively. 



The well waters contained from little or nothing 

 up to 176 units of emanation, averaging 60 units 

 for the twenty-three examined, dissolved radium 

 not being detectable. For comparison may be 

 rited the figures 130 and 196 units obtained by 

 Satterley for two of the well waters of Cambridge 

 (Ilngland). The springs, excluding those of Banff, 

 contained on the average for forty, 120 units, 

 ,45 units being the highest. For these the dis- 

 oived radium was usually very small, rarely ex- 

 ceding 5 or 10 units ; but two springs were 

 exceptional, the Philuder spring of St. Hyacinthe, 

 Ouebec, with 46 units — the highest recorded 

 —and the Carlsbad "Magic " spring, eight miles 

 from Ottawa, with 25 units. All the seven 

 Banff springs examined were uniformly high in 

 emanation content, from 220 to 640 units, with 

 an average of 400 units, the radium content being 

 S5 units, with the exception of the "Auto-road" 

 spring, with 23"5 units, which also had the highest 

 emanation content. Estimates of the flow are 

 given, and in some cases the gases evolved were 

 also examined both for emanation and by chemical 

 analysis. 



Compared with the most radio-active springs 

 known, such as those of St. Joachimsthal, near 

 the famous pitchblende deposits, at Plombi^res 

 (France), Bath (England), and the hot springs of 

 the Yellowstone Park and Arkansas, or of the 

 majority of the spas celebrated for their medicinal 

 powers, none of the Canadian springs are so radio- 

 active. The water of the King's Well, Bath, for 

 example, has an emanation content of 1730, and 

 a radium content of 139. The Quebec and Ontario 

 springs are, however, of the same order in emana- 

 tion content as the group of springs at Saratoga, 

 X.Y. The Banff springs are regarded as re- 

 sembling closely the Bath springs both in mineral 

 constituents and in the character of the gases 

 evolved, with an emanation content about one- 

 fourth or one-fifth as great. Banff being probably 

 the chief Canadian" health resort of the future, 

 owing to its magnificent surroundings, it is sug- 

 gested that the hot springs should be utilised in 

 the manner now adopted at Bath. No results 

 \\ ere obtained such as might indicate the existence 



f radio-active minerals in the neighbourhood of 

 the springs, Canada being apparently exception- 

 ally poor in such minerals, and the waters are 

 in no case suited for bottling as radio-active waters, 

 owing to their poverty in dissolved radium. 



F. S. 

 NO. 2523, VOL. lOl] 



OF. 



PROF. E. A. LETTS. 

 E. A. LETTS, of Queen's University, 



■^ Belfast, died on February 19 in his sixty- 

 sixth year as the result of a cycling accident in 

 the Isle of Wight. 



After a distinguished career at King's College, 

 London, in Vienna and Berlin, Prof. Letts was 

 appointed chief assistant at RIdinburgh University 

 in 1872 at the early age of twenty. Four years 

 later he became the first professor of chemistry 

 at University College, Bristol, and in 1879 he 

 was appointed professor of chemistry at Queen's 

 College, Belfast, in succession to the late Thomas 

 Andrews, F.R.S., which position he held until 

 failing health compelled him to resign early last 

 year. 



Prof. Letts was a man of singular personal 

 charm, and inspired immense respect and affec- 

 tion in his students, to whom he was not merely 

 the kindly teacher, but also the sympathetic , 

 friend who interested himself in all their affairs. 

 He took a large part in establishing the Students' 

 Union in Belfast, and was also prominently 

 identified with the Better Equipment Fund, which 

 aimed at raising ioo,oooL locally for the provision 

 of laboratories and other essential needs of the 

 college. What this fund has meant to the college 

 only those can appreciate who studied or taught 

 under the conditions prevailing before its incep- 

 tion. 



The scientific work of Prof. Letts covered much 

 ground. He possessed great experimental skill, 

 and an out-of-the-way problem, or one involving 

 an unusual amount of manipulative dexterity, 

 attracted his immediate interest. Early in his 

 career he did much work upon the troublesome 

 group of the phosphines. Later, he devoted some 

 attention to the accurate determination of carbon 

 dioxide in water and air, with the result that he 

 was asked to devise the methods to be employed 

 by the first Scott Antarctic Expedition in exam- 

 ining the atmosphere, and to report upon the 

 results obtained. 



Prof. Letts was best known, however, as an 

 authority on questions connected with the 

 pollution of rivers, especially of estuaries and 

 tidal waters. During his thirty-seven years' 

 tenure of the chair of chemistry at Belfast he had 

 ample opportunity for the study of the problems 

 associated with the rapid growth of the city and 

 the insanitary conditions that afterwards de- 

 veloped in the upper reaches of Belfast Lough. 

 These investigations, extending over many years, 

 led to the publication of several papers on points 

 of scientific interest, which were inquired into by 

 Prof. Letts and his students. Perhaps the more 

 interesting of these discuss the relation of the 

 marine alga Viva latissima to the nitrogen content 

 of the water in which it grows. The decay of this 

 seaweed on the foreshores of the Lough was 

 found to be the cause of the nuisance rather than 

 the direct pollution of the water by sewage. At 

 the request of the Royal Commission on Sewage 

 Disposal, Prof. J.etts, in collaboration with Dr. 



