2 
When the cells are discharged during the welding the 10 groups are in parallel, 
and by means of a switchboard the number of cells in series in each group can 
be reduced by five at a time. Thus leaving 45, 40, 35 and so on cells in series 
in each group. The operators wear thick leathern gloves and a leather mask, 
with darkened glass eye-holes, to protect the hands, the skin of the face, and the 
eyes respectively. Tor convenience sake this mask is only worn at the moment 
of electric contact, and the preliminary operations are carried on without it. We 
will take as an example of this process the welding of a tube for a piece of 
ordnance by the aid of the voltaic arc. Tor this purpose plates are bent to 
calibre with their longitudinal edges meeting each other. The edges are cut 
obliquely, thus forming a trough along the outside of the whole extent of the 
future welding. The actual welding is performed as follows :—Having con¬ 
nected the future tube with the negative pole, the sides of the trough and pieces 
of iron placed thereon are touched with the positive electrode in the handle. 
The handle is then withdrawn, and the arc is struck. In consequence of the 
high temperature the iron is instantly fused, and fills up the trough. The surface 
of the welding is forged and levelled with a few blows of a hammer. Then 
again fresh iron is introduced, melted as before, and forged and levelled as before. 
This operation is continued until the whole of the trough is filled up with melted 
iron, and a perfectly welded tube is formed from the bent iron plate. Thus, 
thanks to the process we have described in detail for iron and generally for tubes 
of other metals, the simple and quick method of electric welding has been sub¬ 
stituted for the slow and difficult method of casting. When tested the fracture 
at the weld is similar to that of the plates themselves, and in some cases the 
fracture has occurred in the plate instead of at the weld. 
The method of Benardos furnishes a means of joining together different metals 
without the employment of solder, which might be injurious as well as incon¬ 
venient. Thus it is possible by means of the above process to substitute for 
thick copper pipes tliin iron ones lined with copper. 
Up to the present time it has been considered impossible to weld the broken 
cast-iron portions of engines, stands, etc. By means of the above process such 
an operation is now practicable. 
The chief objection to the employment of this process is that the voltaic arc is 
rich in chemically-acting rays, which act most injuriously on such sensitive tissues 
as the surface of the eye and the skin of the face and hands, etc. ' But measures 
can be taken to neutralise this action, as above described. Turthermore, not 
everyone is equally sensitive to it. 
The method of Slawianoff is, in the main, similar to the above, and differs 
from it only in detail. He uses pencils of metal in place of carbon, and in filling 
up the trough, instead of adding .the metal in layers, he prevents the fused metal 
cooling until the whole trough is filled up. Turthermore, whilst Benardos always 
connects the anvil with the negative pole so as to render the oxidation of the 
object impossible, Slawianoff changes the poles about twice during the operation, 
though before the completion of the operation the whole of the object must be 
negative. The chief advantages of electric welding are that metals such as 
wr ought-iron, platinum, etc., which can only be fuzed with the greatest difficulty, 
can by its aid be joined together without the employment of solder, the process 
is inexpensive, expeditious, and does not require much apparatus. 
As an instance of the application of the process of Slawianoff may be cited 
the repair of the Tsar Kolokola, 1 or great bell of Moscow. 
A fuller account of Slawianoff’s method may be found in the brochure “ Die 
Herstellung von Metallgussmittelst Melctricitat nach dem Verfahrew des Derg” 
Ingenieur Nikolai Slawianoff. 
1 Literally Emperor of Bells. 
