505 
ACTION OF WATER ON ZINC, ETC, 
adds that the facts drawn from toxicology, naval hygiene, 
public hygiene, and therapeutics, all attest the innocuity of 
water that has rested upon zinc. In consequence, the use of 
zinc and galvanized iron cisterns, of zinc pipes, and of gal¬ 
vanized iron pipes, for the conveyance of water, cannot be 
considered dangerous to health. 
Others, nevertheless, hold a different opinion. Pappen- 
heim* states that, though the amount of zinc present in such 
waters as have been spoken of is not always sufficient to 
produce poisonous effects, since it is indubitable that they 
have frequently been employed for considerable lengths of 
time with impunity, yet the amount of metal taken up by 
large quantities of water may be sufficient to produce dele¬ 
terious results. He states, moreover, that in France, spite 
of Fonssagrives* assertions, the water tanks of ships have had 
to be regalvanized and tinned, and that zinc vessels have to 
be especially avoided. Dr. Parkes likewise states + that Dr. 
Osborne, of Bitterne, has frequently observed injurious effects 
from the use of waters impregnated with zinc. 
Of the fact that water does, under certain conditions, act 
energetically upon zinc and upon galvanized iron, I have had 
abundant evidence. Some months ago I was consulted by a 
gentleman relative to the water-supply to his house. The 
existing 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 re¬ 
mote 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, 
galvanized 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 galvanized 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. 
* * Handb. d. Sanitatspolizei,’ B. ii, p. 765. 
f ‘Manual of Hygiene/ 3rd edit,, p. 12. 
