BY J. BROWNLIE HENDERSON, F.I.C., F.C.S. 141 



abundant evidence. Some months ago I was consulted by a 

 gentleman relative to the water supply to his house. The exist- 

 ing supply, from a well on the premises, furnished an excessively 

 hard, chalky, and seleniferous water. It being desirable, for 

 many reasons, to have a soft water, I advised that the rain water 

 from the extensive slate-covered premises should be filtered and 

 stored for use, as the house was remote from possible sources of 

 contamination of the rain water. As a matter of precaution, I 

 recommended the use of iron pipes for conveying the water, and 

 that, after filtration through charcoal, sand, and gravel, the 

 water should be stored in a tank lined with asphalt. Against 

 my knowledge, galvanised iron pipes were used instead of those 

 of iron only. The consequence of this has been that the water 

 passing from the reservoir through the galvanised iron pipes 

 has for many weeks been turbid and milky in appearance. It 

 contains a notable quantity of zinc in suspension, and some in 

 solution. I may remark that zinc in solution in potable waters 

 is best detected by the addition of potassic ferrocyanide to the 

 clear water after acidulation with hydrochloric acid, when a 

 whitish cloud will immediately form if zinc be present. Of 

 course this reaction must be confirmed by other and well-known 

 tests. I know of no test for zinc which is so delicate as this. 



" What might be the effect of drinking such water as I 

 have described I cannot say, for no one would touch it if other 

 water were to be obtained. Probably, its continued use might 

 be productive of injurious eft'ects. 



"Engineers should bear in mind this effect of rahi water 

 upon zinc and upon the so-called galvanised iron." 



On page 115 of same volume Dr. P. F. Frankland 

 terminates a note on the subject by declaring that the storage of 

 tain water in galvanised iron tanks is probably attended with 

 some risk. 



In Vol. 51 of the Cheiiucul Neirs, page 18, the full text of 

 Dr. Venable's article, quoted above by Thresh, appears. 



I examined the Lancet, The Practitioncy, and the British 

 Medical, Journal so far as I could get them back to 1890, but 

 with the following exception found nothing of importance. In 

 the British Medical Journal of 7th September, 1901, page 615, 

 is an article by Dr. Gimlette on an epidemic of zinc poisoning 

 in the tropics. The following is an extract from the article : — 



" The poisonous efl'ects of various salts of zinc have been 

 demonstrated from time to time. In England they have been 



