188 DOMESTIC WATER SUPPLY OF BRISBANE, ETC. 



clover, vetch, and buck-wheat. In soils, those rich in humus 

 render the zinc insoluble so that it has little harmful effect, 

 but in ordinary sandy soils, watering with water containing 20 

 parts of zinc per million after six weeks gradually killed off 

 cabbages, peas, and even grasses. The action seems to arise 

 through destruction of the chlorophyll, as zinc has no deleterious 

 effect on the development of vegetation in the dark or on plants 

 containing no chlorophyll. 



Vol. IV., p. 461, gives a record by three other investigators, 

 who confirm the above results. 



Vol. v., p. 498, records the presence of zinc in dried apples. 

 No proportions given. 



Vol. VI., p. 557. — Bunte says the use of galvanised iron 

 pipes for household water did not give enough zinc to be in 

 any way harmful, but gives no figures. 



Vol. VII., p. 689. — Max Muller found water from a copper 

 roof to corrode zinc quickly, while water from a slate roof 

 did not. 



Vol. XI., p. 363. — \. H. Allen found "a large proportion 

 of zinc in peas, which he found free from copper." 



Vol. XVIII., p. 102. — H. E. Davies, after a long investiga- 

 tion established the following facts : — 



(1) All kinds of water attack zinc in presence of air, 



(2) Rain water appears to have the least action. 



(3) A moderate degree of hardness favours the action, 



and extreme hardness does not prevent it. 



(4) Coating the zinc with deposit does not altogether 



stop the action. 



(5) When water containing zinc is drunk, zinc is found 



in all the viscera. 



The article also proves that the action of water on zinc is 

 much accelerated by the presence of nitrates. 



The Chemical News contains very little information up 

 to Vol. 49. On page 85 of this volume the following article appears 

 by Dr. Heaton. This article is quoted in most of the text books 

 when referring to zinc in tank water: — 



" The water supplied to Cwmfelin, near Llanelly, is drawn 

 from a spring at Penderry, and carried for about half a mile 

 through a galvanised iron pipe. Mr. J. Raglan Thomas, the 

 Medical Officer of Health for the district, detected zinc in the 

 water of this pipe, and sent me samples from the spring and 



