MAGAZINE OF SCIENCE AND ART. 
105 
Swamp, with about six grains of impurity per gallon, 
dissolved five times the quantity of lead under similar 
circumstances. AVater from North Rocks, Parramatta, 
containing 19 grains of dissolved matter per gallon, 
took up six times the quantity of lead; and, not to 
multiply examples, the water from a deep well at the 
University, containing per gallon 34$ grains of dis¬ 
solved matter, took np nearly 20 times the quantity of 
lead first indicated. - 
But while these cases afe sufficient to show that a 
water is not dangerous in proportion to its purity, they 
must not be taken as proving the reverse, namely, that, 
in contact with lead, a water is dangerous in proportion 
to its impurity—though this opinion has also been 
advocated. 
The condition of a water as to hardness or softness 
has been thought to affect the action on lead: but while 
some have said a rvater is dangerous in proportion to its 
softness, others have said distinctly the opposite, that a 
water is dangerous in proportion to its hardness. My 
own observations go to prove that a knowledge of the 
hardness or softness of a water enables us to predicate 
nothing respecting its action upon lead. 
Organic matter has also been considered influential in 
determiningthis action. I have not been able to form a 
distinct opinion on this head, for though some of my ex¬ 
periments may favour, others seem to go rather against 
the supposition that the amount of action upon lead is 
proportional to the amount of organic rnattur in the 
water. 
The nature of the lead of which pipes and cisterns 
are made, has evidently much to do with the action of 
water upon them. Commercial lead, as I have already 
stated, is never quite pure, and it is rcasonablo to sup¬ 
pose that the kind and quantity of the impurities would 
sensibly affect the facility of its corrosion by water. 
Accordingly, I found in the course of my observations 
that no definite and constant relation could be traced 
between the length of a pipe and the quantity of lead 
dissolved by water flowing through it. In further elu¬ 
cidation of this point, I Gad rods cast of commercially 
pure lead, of the same lead with 6 per cent, of vine, and 
of the same with 6 per cent, of tin. I made several 
experiments with these rods, and always with uniform 
results. The pure lead got tarnished, but the water was 
very little contaminated. The alloy of lead and tin 
remained quito bright; the water also remained clear, 
hut a considerable quantity of lead was nevertheless 
dissolved in it. The alloy of lead and zinc acquired a 
coating of a soft win to substance, which was easily 
rubbed off, leaving the surface bright; a sediment of 
the same white substance lay on the bottom of the ves- 
sei, and the water was quito milky, yet not a particle of 
lead was found in the water. The white deposit was no 
doubt oxide or carbonate of zinc, but I did not examine 
it minutely. In one of these trials, the rods were im¬ 
mersed in Sydney water, each in one pint, and left for 
45 hours. The water in which the pure lead had rested 
contained about 5 degrees of lead; there was no milki¬ 
ness in the water, nor any sediment. The water in con¬ 
tact with the alloy of lead and tin was also quite clear 
and free from sediment, but contained 20 degrees of 
lead. The remaining specimen of water, with the alloy 
of lead and zinc, was quite milky, and there was a 
plentiful white deposit, but no trace of lead in the wa¬ 
ter. These facts are very interesting, and, I believe, go 
far to explain those remarkable discrepancies between 
different experimentalists that I have previously alluded 
to. The explanation of these curious facts is doubtless 
that lead is electro-positive to tin, and electro-negative 
to zinc, so that the lead is 7?iore acted upon when in con¬ 
tact with tin, and less acted upon in contact with zinc, 
than it would be by itself. 
2. AYe proceed now r to consider the extent to which 
lead may exist in water, without being injurious to the 
health of those that habitually use the water. It is at 
once obvious, that this question is not susceptible of a 
definite answer. Age, constitution, quantity and con¬ 
dition of the water imbibed, and other circumstances, 
will so modify the results, that in no two cases may 
they be exactly alike. Yet, it is of importance to 
know' how small a quantity of lead has, in any one in¬ 
dividual, given rise to had effects, for then we ought, in 
common prudence, to account such a proportion, of lead 
unsafe, and avoid the use of the water containing it. 
Now, the smallest recorded quantity of lead that has 
notably injured health, is one-ninth of a gram per 
gallon, or one part of lead in 630,000 parts of water. 
As the case where this was established is a very inter¬ 
esting one, I will quote the account of it by Air. W. 
Herapath of Bristol, in a letter to the Times of 14th 
September, 1850:—“In the west of England a river, the 
water of which had been used from time immemorial 
by the inhabitants of a village on its banks without in¬ 
jury, was found to affect their health; symptoms of 
indigestion abounded, with loss of flesh and appetite, and 
there were some few cases of colic. They believed that 
it arose from the use of the river -water, as those who 
used water drawn from a spring at some distance weve- 
not so affected. I was requested to analyse the river 
water, and found iu it 1-500,OOOths of carbonate of lead 
[that is equal to 1 grain of metallic lead in about 9 
gallons of water, or 11 degrees of lead], w’hich arose 
from a mine worked at the distance of 3 or 4 miles from 
the village, on the other side of a range of limestone 
hills.” 
It is true that Dr. Christison of Edinburgh quotes 
approvingly a statement by Dr. Thomson to the effect 
that, “when the quantity of lead docs not exceed 
1-600,OOOths, or a millionth part of the water, it is 
ridiculous to imagine that any harm (.an result to man 
from the constant use of it for domestic purposes,”—but 
when Dr. Thomson characterises the opinion as “ ridicu¬ 
lous” he must simply mean that it is not very probable. 
In the above quoted case, however, we find that less 
than 1-600,OOOtli of lead resulted in manifest harm to 
a considerable community. 
In a number of cases of apparent lead poisoning that 
have occurred in Sydney, I have found lead in the 
water made use of by the sufferers, in quantities vary¬ 
ing from 20 degrees to 100 degrees. In some cases tf.e 
lead has, I tlnnk, not exceeded 15 degrees, but the 
symptoms were more obsenre. On the other hand, I 
once met with a case at home where a family were in 
the habit of using water containing 5 degrees of load 
without any obviously injurious results. I think we 
may conclude that a water containing 10 degrees of 
lead (1 of lead in 700,000 parts of water) is unsafe, and 
should be avoided. AYc might, indeed, be justified in 
condemning the habitual use of water with even 5 
degrees of iead. 
3. To what extent is the water of Sydney' liable to 
contamination by contact with lead? 7*0 elucidate this 
point, I have made many' experiments, probably more 
than 50, on water delivered through lead service pipes. 
The pipes have varied in length from 18 to 455 feet; 
some newly laid, and others in the ground for different 
periods up to 12 or more years. The specimens of 
water have been drawn iu different conditions—some 
the first in the morning, other, when the pipes have been 
in frequent use. The quantity of lead in the water has 
been found to vary from notliing, or a mere trace, 
up to 100 degrees; but no definite relation can be es¬ 
tablished between the length of the pipe, or its oge, and 
the quantity' of lead dissolved. As might be expected, 
the amount of lead has been found to increase with the 
time the water remains at rest- in the pipe. In many' 
of the eases examined the lead was in larger proportion 
thau 10 degrees and therefore dangerous. I have made 
many experiments also on water of deep wells, in and 
around Sydney, pumped up through lead pipes. In 
such cases the risk of contamination is very' great, as 
the lower end of the suction pipe is continually in the 
water; hut the result is by no means uniform : the 
water in some cases being little injured, and in others 
containing more than 100 degrees ot lead. 
From all these experiments, and from conversations 
with various medical men, I am of opinion that much 
