18 REPORT—1890, 
when these are added in small proportions to copper and certain of its 
alloys, the de-oxidation of which, through the agency of those substances, 
results in the production of sound castings of increased strength and 
uniformity. It is only when present in small proportion in the finished 
steel that aluminium increases the breaking strain and elastic limit of 
the product. 
The influence of aluminium, when used in small proportion, upon the 
properties of grey and white cast iron is also of considerable interest, 
especially its effect in promoting the production of sound castings, and 
of modifying the character of white iron in a similar manner to silicium, 
causing the carbon to be separated in the graphitic form; with this 
difference—that the carbon appears to be held in solution until the 
moment of setting of the liquid metal, when it is instantaneously liberated, 
with the result that the structure of the cast metal and distribution of 
the graphite are perfectly uniform throughout. 
The probable beneficial connection of aluminium with the industries 
of iron and steel naturally directs attention to the great practical im- 
portance, in the same direction, which is already possessed, and pro- 
mises to be in increasing measure attained, by certain other metals 
which, for long periods succeeding their discovery, have either been only 
of purely scientific interest and importance, or have acquired practical 
value in regard to their positions in a few directions quite unconnected 
with metallurgy. Thus, great interest attaches to the influence of the 
metals manganese, chromium, and tungsten upon the physical properties 
of steel and iron. 
The rame of Mushet is most prominently associated with the his- 
tory of manganese in its relations to iron and steel. Half a century 
ago David Mushet carried out very instructive experiments on the in- 
fluence exerted upon the properties of steel by the presence of man- 
ganese; and to Robert Mushet we owe the invaluable experiments 
leading to his suggestion to use manganese in the production of steel 
by the Bessemer process, which at once smoothed the path to the 
maryellously rapid and extensive development of the applications of steel 
produced by that classic method, and subsequently by the open-hearth or 
Siemens-Martin process—a development which has recently received its 
crowning illustration in the completion of one of the grandest of existing 
triumphs of engineering science and constructive skill—the Forth 
Bridge. 
Robert Hadfield has recently contributed importantly to our knowledge 
of the relations of manganese toiron. His systematic study of the subject 
has revealed some very remarkable variations in the physical properties of 
so-called manganese-steel, according to the proportions of manganese 
which it contains. Thus, while the existence in steel of proportions: 
ranging from 01 up to about 2°75 per cent. improves its strength and 
malleability, it becomes brittle if that limit is exceeded, the extreme of 
