SCIENCE ON THE CONTINENT, 
529 
conclusions, says M. Caron, are confirmed by practice, for the minerals 
which yield the best steel frequently contain sulphur, but never phos- 
phorus ; and moreover it is remarkable that, although they contain coppery 
pyrites, the iron derived from them never contains sulphur. Manganese 
has, beyond question, the effect of rendering steel better and, above all, 
more durable ; and this power is not difficult of explanation. When a 
sufficient quantity of manganese is added to grey cast-iron, of which the 
carbon is principally in a free condition, the result is white iron, in which 
the carbon is almost entirely in a state of combination. The effect is the 
same in the case of steel : a very small quantity of manganese is sufficient 
to retain the carbon in a state of combination, and to give to the metal 
those conditions which characterize steel of good quality. But the steel 
should never contain more than one two-hundredth part of its own weight 
of manganese, otherwise it becomes hard and brittle, the fracture assumes 
a crystalline appearance, and the metal loses a great part of its tenacity. 
Manganese has, moreover, the property of rendering steel capable of being- 
welded, which is not so without its aid. It is not uncommon, in order 
to improve the quality of iron, to mix ordinary and manganesian iron 
together, and then to refine the mixture ; and M. Caron says that he has 
learnt by experience that the purifying power of the manganesian iron is 
in direct proportion to the amount of the manganese present. It is there- 
fore most important, he adds, to reduce the manganesian ores in such a 
manner as to retain the largest possible quantity of manganese in the iron. 
The spathic iron ore of Siegen contains 15 to 20 parts of manganese to 
100 of iron, and yet the cast-iron derived from this mineral only contains 
from 6 to 7 per cent, of manganese ; but if, by a modification of the 
furnaces, or a change in the nature or proportions of the fluxes, the 
amount of the manganese in the iron could be raised to 10 per cent., it is 
certain that cast-iron of very great commercial value would be the result.* 
M. Caron promises further communications on this very important 
subject in a short time. 
Pheserv.vtion of Wood. — Considerable attention has been given of 
late to this important subject in France and Belgium, and M. Pottier, of 
the University of Ghent, has recently presented a memoir on the effect 
of the creosote process to the lloyal Academy of Belgium. He therein 
details his experiments with the heavy oil of gas-tar, and arrives at the 
conclusion that of the various ingredients which enter into its composition, 
the volatile hydrocarbons, aniline, plienic acid, and napthaline possess no 
preservative qualities whatever ; and that the green oil which is produced 
by the distillation of gas-tar at a temperature of about 570° is that which 
is most effective in preventing the destruction of wood. 
M. Lapparent, Director of Naval Construction in France, has been 
engaged in investigating the subject from another point of view. Having- 
been impressed with the effect of the old method of charring posts and 
other timber to be fixed in the ground, he made a series of experiments on 
the causes of the destruction of timber and the action of carbonization as 
* See also Summary of Metallurgy, 
