104 
MAGAZINE OF SCIENCE AND ART. 
intTTO. Micaceous specular iron, countv-of Wellington. 
Fibrous radiating black ho-niati/o iron ore, from Daw's 
Plains. Compact brown hounatite, from Cliurch and 
School Estates, and from tho coal measure sandstone, 
of the Bremer River. Reniform otide of iron in con- 
cretionary ma&sos in sandstone, near Murrumbidireree. 
Liinonite, from Cooiubing. Nodular or pebble-limned 
red oxide ot iron, found on the surface of the ground ia 
vast quantity, near Macquarie River. 
5. .Bog iron ore, Carcoar, &c. 
G. Ilwenite, or titanic iron, from tbe countv of 
Bligh. 
7 • Iron sand, with emery (corrundum) from gold 
washing streams. 
Amount of Iron imported (manufactured and un¬ 
manufactured) during the past year, according to the 
Custom Returns. 
Iron and steel. £19G r W2 
Hardware and ironmongery. 233,718 
Machinery .. 53,717 
Ditto for mills. 2,152 
Ditto for weighing ...„. 2,805 
£489,034 
The discussion that has recently arisen as 
to the purity of the water supplied to Syd 
ney, seems to render this an appropriate 
time to re-print the important paper on the 
subject which was read by Professor Smith, 
of the University, on Wednesday, August 
13, 1856. 
ON THE ACTION OF SYDNET WATER UPON 
LEAD. 
In this paper I treat briefly, and with a view to prac¬ 
tical application, of the four following questions:— 
1. AVhat determines the action of water upon lead 
generally ? 
2. To what extent may lead exist in water without 
being injurious to health ? 
3. To what extent is Sydney water* liable to be con¬ 
taminated by contact with lead pipes and cisterns ? 
4. How may this contamination bo prevented or re¬ 
medied? 
I must premise that, to avoid circumlocution, the 
quantity of metallic lead in any form of combination, 
dissolved or diffused in water, is expressed in this paper 
in degrees. By ono hundred degrees of lead, I mean 
metallic lead in water, at tho rate of one grain to a gal* 
Ion . Bv one degree of lead, I mean lead at the rate of 
1-100th of a grain per gallon, or one part of lead in 
7,000,000 parts of water ; and I have adopted tlus quan¬ 
tity as one degree, chiefly because it is the smallest 
S n’tion of lead that can be readily estimated in my 
od of experimenting, 
First, what determines the action of water upon lead 
generally ? After having collated tho experiments and 
opinions of numerous authorities on this snbject, and 
having performed many experiments myself for its 
elucidation, I am forced to tho conclusion that no exact 
and complete answer can at present he given to the 
question. The problem is evidently a complicated one. 
It is not simply to determine how chemically pare wa-. 
ter will act on similarly pure lead, bat liow natural 
waters, containing usually 10 or 12 different compounds 
dissolved in very various proportions, will act on the 
common lead used in fabricating pipes and cisterns. 
As to the solution of this problem no two investigators 
are agreed. Each fresh inquirer sets himself to correct 
•what he terms the “ erroneous statements" of his pre¬ 
decessors ; and so remarkable is the diversity, not only 
of opinions but of experiments, that there seems to be 
scarcely a single fart well established and generally al- 
mitted. One is curious to know the reason of such dis¬ 
crepancies. My own impression is, tint experiments 
have been too much confined to artificial solutions, 
which never properly represent the products of nature; 
and that observations on natural waters are neither suf¬ 
ficiently numerous nor accurate. Another obvious 
source of disagreement is, that commercial lead is never 
quite pure, and its relation to water is affected by the 
nature and projwrtion of the impurities. 
The following points may lie noted as beating upon 
the question under consideration, and helping towards 
its solution. B is pretty generally admitted (and mv 
own experiments accord with tl>e opinion) that one of 
tlie chief agents in the corrosion of lead by water is 
free carbonic acid. This gas- may be derived*from geo¬ 
logical sources, or it may be absorbed from the atmos* 
phero. Supplied somehow from tlwj earth, it usually 
abounds in springs* and this may explain why, as a 
general rale, lead is more dangerous with spring waters 
than with river and surface waters. The absorption of 
carbonic acid from the atmosphere seems to go on with 
most facility in the case of the purest waters, and such 
waters, when charged with the gas, are cominpnl v found 
to act energetically upon lead. Agitation, however, is- 
unfavourable to the retention of carbonic acid, and 
hence river waters are tolerably free from it. A dis¬ 
tinction must here be drawn between simple corrosion 
of lead, and its- solution in water. By the action of 
oxygen and carbonic acid, lead is- converted first into 
oxide and then into carbonate, but the carbonate is al¬ 
most insoluble in water, and will subside as a white 
powder if cot kept in suspension by agitation. The 
solution of lead in water must, therefore, be effected by 
other agencies, but what these are we are not in a posi¬ 
tion to state; experiments and opinions being as yet too 
contradictory. I am inclined to think that the chlorides 
occasionally assist in dissolving lead,—chloride of cal¬ 
cium, for example (a salt frequently existing ia water) 
—I found had distinctly such an effect. In two par¬ 
allel experiments, clear rain water acquired five degrees 
of lead jin 2-1 hours, while the same water with chloride 
of calrinm dissolved in it at the rate- of four grains to 
the gallon, took up 10 desrrees of lend iu the same 
time—both waters being filtered before the lead was 
estimated. Similar trials with common salt (chloride 
of sodium), went to show that it rather hindered tho 
solution of the lead; but I would by no mean* accept 
a few experiments on artificial solutions as decisive on 
this point.* 
I think it needless, for the purposes of this paper, to 
dwell on this part of the subject, as a comparison of all 
the facts that have come under my notice would justify 
no other conclusion than this, uaxnelv, that with the 
analysis of a given water before us we cannot tell, with¬ 
out actual trial, whether such water would act injuri¬ 
ously on lead or not, No more can be done than simply 
to indicate on which side tho probability is, and in many 
cases that can be no better than a mere guess The 
common statement made in chemical books that, in pre¬ 
sence of lead, a water is dangerous in proportion to its 
purity, is certainly not borne out by facts. One of the 
purest waters in Britain,—a water containing on an 
average only 3$ grains of dissolved solid matter per 
gallon—has a very trifling action on lead. A specimen 
of water from the Hawkeshury at Windsor, containing 
5 grains per gallon of dissolved matter, I fonnd had 
about thn same action. The water of the Lachlan 
* By " Sydney water" I mean that distributed from the 
tunnel communicating with the Lachlan Swamp. 
In those experiments the decomposition of the car¬ 
bonate of lead seems to be determined by the insolubrity 
of the new carbonate formed. When chloride of calcium 
used, it is probable that carbonate of lime is precipitated, 
while chloride of lead remains in solution. Other earthy 
chlorides would likely act in a similar manner. With 
alkaline chlorides, again, there seems to be no decompo¬ 
sition, as the alkaline carbonates are soluble. 
