TRANSACTIONS OF THE SECTIONS. 55 
—as one of great importance, and he strongly commends it to the notice of chemists 
and electricians as a subject still requiring to be worked out. It would appear that 
the necessary use of solder,—the presence of portions of other metals than lead in 
any form in contact with lead,—inequalities in the surface of the lead sheeting,—the 
use of lead from different factories and of different composition (as lead made with 
old solder, or containing silver unextracted),—may each and all determine galvanic 
action, which facilitates, to a dangerous degree, the corrosive action of hard water 
on lead. What renders galvanic action the more dangerous and the more important 
is, that it is strongest in hard waters, that is, in those containing more or less neutral 
salts, which, under other circumstances, would exert their usual protective influence 
on the lead. 
The paper contains several illustrations of,—1. corrosion or erosion, to such an 
extent as to cause repeated leakage, of leaden cisterns, by waters of various degrees 
and kinds of hardness, or containing various kinds and amounts of neutral salts ; 
and 2. the poisonous action of such water, when impregnated with lead, on the 
human body. It also contains a series of comparative chemical analyses, made with 
a view to ascertain the condition as to hardness, or the nature and amount of the 
saline constituents, as well as the action upon lead, of various waters used for culinary 
and drinking purposes in and around Perth. 
The author refers to the mechanical and chemical means of protecting the lead 
of cisterns and pipes against the corrosive action of water. Of mechanical means, 
he gives as illustrations the coating of the lead with compositions of rosin and tallow, 
or similar substances ; and the patent processes of Mr. Davis of Lambeth, London, 
for lining the interior of leaden pipes with tin, or with gutta percha, caoutchouc, 
gum-lacs or bitumen. The substitution of other metals—of wood, glass, earthenware, 
or gutta percha for lead—in the construction of cisterns and pipes, is also referred to. 
Of chemical means, he instances the addition to the water of powerfully protective 
salts, such as the phosphate of soda, or the iodide of potassium in minute propor- 
tion. 
The author believes that cases of lead poisoning, in a minor degree, are still con- 
stantly occurring in all our large towns from the plumbeous impregnation of our 
drinking waters; and he impresses the necessity of inquiring at once into the con- 
dition of the water supply whenever obscure colic or paralytic complaints exhibit 
themselves, otherwise inexplicable, especially if it be found that several persons are 
simultaneously affected*. 
On an improved Electric Lamp invented and manufactured by Mr, W1LL1AM 
Hart, Edinburgh. (Communicated by Dr. StEvENSON MacapaAm, 
RSE.) 
- The relation which the several parts of this lamp bear to each other, will be better 
understood by following the route which the electricity takes in its travels through 
the lamp. The wire attached to one of the extremities of the battery is brought to 
a binding-screw, which is in metallic connexion with the cylindrical base of the 
arrangement and the lower charcoal rod. The latter is immoveable, and constitutes 
one of the poles of the voltaic battery. The wire coming from the opposite end of 
the battery is placed in a connecting screw (which is insulated from the cylindrical 
base by the insertion of a ring of ivory), passes up the centre of a hollow stem (also 
insulated from the cylindrical base by ivory), is led through a canal in the centre of 
an arm placed at right angles to the stem, and is then wound round an electro- 
magnet suspended in a vertical position from the arm. ‘Thus far the wire is covered 
with silk, and hence does not come into metallic connexion with the other parts of 
the lamp; but having completed its required course, it is soldered to the electro- 
magnet, and thus becomes metallically connected with the upright stem and all its 
appurtenances, including a file-like rod, grasping the upper charcoal rod, which is 
moveable and forms the second electrode. 
When the battery is not in action, the roughened or file-like rod, with its attached 
upper carbon pole, is not upheld by any device, but simply reclines on the lower 
* The paper will be found published at length in the “ Edinburgh New Philosophical Jour- 
nal” for April, 1859. : : 
