BY J. BROWNDE HENDERSON, F.I.C., F.O.S. 133 



when applied to this water, as they nhoke up almost at once 

 and after a short time hecoiue permanently choked. TheEnog- 

 gera water then, although not liable to be contaminated with 

 typhoid, cholera, or other pathogenic germs, may be classed as 

 unsuitable for drinking. If the water is allowed to run until 

 clear, the sample then collected, boiled, filtered, and allowed 

 to stand for twenty-four hours, it is generally palatable, though 

 even after this treatment it may have an objectionable odour. 



With Enoggera and Gold Creek waters nearly always, and 

 Mt. Crosby sometimes unsuitable for drinking, the rain water 

 collected from galvanised iron roofs in galvanised iron tanks 

 is the principal source of drinking water in Brisbane, even 

 where the other supplies are available. 



Organically tank water is nearly always very pure ; in fact, 

 I have never yet found a tank water as bad organically as the 

 ordinary Enoggera or Mt. Crosby. The only objectionable ingredi- 

 ent I have found in tank water is zinc. This metal is always 

 present, generally in the form of carbonate, and varies in amount 

 from about 03 to 2 grains per gallon in ordinary waters, though 

 water collected from new tanks or from new roofs, often contains 

 much more, and deposits a thick white sediment of hydrated 

 zinc carbonate in the bottom of the tank. My main object in 

 reading this paper to-night is to call the attention of our 

 medical members to the presence of this zinc. I have at 

 various times spoken to several medical gentlemen on the 

 subject, but no one seems to have given it any attention. 

 Now I do not in any way want to raise a scare, as that 

 generally does more harm than good, but from my investi- 

 gations on the matter I think it is well worthy of serious 

 study, particularly in the case of medical men dealing with 

 children. 



When I first realised that all the tank waters contained so- 

 much zinc I naturally felt alarmed, but concluded that as no 

 one had ever noted poisonous effects from the use of such 

 waters in Brisbane, there were no poisonous effects. When 

 the Lead Poisoning Commission was appointed some years ago, 

 as a member of the Commission I gave the matter a good 

 deal of attention, and smce then I have gradually been forced 

 to the conclusion that the zinc may not be so harmless as ia 

 generally believed. 



