Zinc coatings on the surface of galvanized iron pipe are attacked and dissolved by some waters almost as energetically as is lead pipe. Zinc is also dissolved to a considerable extent from brass pipes. At Cwmfelin,* in Wales, galvanized iron pipe that conducts water from a spring to the town, a distance of one-half mile, was found to change the character of the water as shown by the following analysis:
At Spring At Delivery
Nitrogen as nitrates..... .8 114
Total residue .... . . 154.3 270
Zinc carbonate .... ... none 91.6
Effect Of Metals On Health
Kind of Pipe Action of Water Effect upon People
Lead pipe..... Dissolves lead Dangerous
Tin or tin lined lead No effect No effect
Galvanized iron .... Dissolves zinc Injurious
Tin lined iron..... No effect No effect
Brass pipe .... Slightly dissolves Objectionable
copper and zinc
Plain iron .... Rusts and dissolves Objectionable
Aluminium No effect No effect
Nickel..... No effect No effect
Benedict nickel .... No effect No effect
The action of water upon galvanized iron pipes is almost as energetic as upon lead pipes, and under suitable conditions will dissolve equal amounts of metal from each. However, the effect of the zinc upon the health is not dangerous but only injurious, because zinc is not a cumulative poison, and so long as the initial dose is not sufficient to cause illness or death, the effect is soon thrown off without apparent injury. Lead, on the contrary, even when taken in small doses, remains in the system until sufficient poison accumulates to cause serious illness or death, or if the initial dose is of sufficient strength the effect may be immediately fatal.
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