42 
NATURE 
[May 11, 1899 
The metallurgy of America is so closely interwoven with our 
own, that I must permit myself a brief reference to four men 
who stand out from the industrial ranks of our kinsmen. These 
are Alexander Lyman Holley, the Hon. Abram S. Hewitt, 
John Fritz, and Prof. Henry Marion Howe. All of them are 
Bessemer medallists. 
It may help us to estimate the value of the labours of the 
four men whose names I have given if we remember that at 
the present time the United States export about a million tons 
of iron and steel a year, while twenty years ago they were not 
exporting any. We may also fairly consider their influence 
on the rapid development of the United States Navy. It would 
seem that we, in this country, in the belief in our insular 
security, had somewhat neglected the art of naval warfare, until 
Admiral Mahan reminded us of what we had done in the past, 
and of our possible course in the future, in a series of writings 
which have done much to convince the two nations, England 
and America, ‘‘ that they are in many ways one.” 
It is time to offer a collective statement of the achievements 
which have either been actually effected or are in immediate 
prospect. 
There are blast-furnaces which will produce 748 tons of pig 
iron in twenty-four hours, with a consumption of little over 
15°4 cwts. of coke per ton of iron. The gases from blast- 
furnaces are used, not only as sources of heat, but directly in 
gas-engines, 
There are Bessemer converters which can hold 50 tons of 
metal, and open-hearth furnaces which will also take 50 tons, 
while 100-ton furnaces are projected. The open-hearth furnaces 
are fed with one ton of material ina minute, by the aid of a 
large spoon worked by an electro-motor. There are gigantic 
‘‘ mixers,” capable of holding 200 tons of pig iron, in which, 
moreover, a certain amount of preliminary purification is effected. 
Steel plates are rolled of over 300 feet in area and 2 inches 
thick. There are girders which justify the belief of Sir Benjamin 
Baker that a bridge connecting England and France could be 
built over the Channel in half-mile spans. There are ship-plates 
which buckle up during a collision, but remain water-tight. 
There are steel armour piercing shot which will penetrate a 
thickness of steel equivalent to over 37 inches of wrought iron. 
The points of the shot remain intact, although the striking 
velocities are nearly 2800 feet a second. There are wires which 
will sustain a load of 170 tons per square inch without fracture. 
Hadfield, whose labours will, I trust, be continued far into the 
twentieth century, has given us manganese-steel that will not 
soften by annealing ; while Guillaume has studied the properties 
of certain nickel steels that will not expand by heat, and others 
that contract when heated and expand when cool. Nickel, 
chromium, titanium, and tungsten are freely used alloyed with 
iron, and the use of vanadium, uranium, molybdenum, and 
even glucinium, is suggested. There are steel rails which will 
remain in use seventeen years, and only lose 5 lbs. per yard, 
though fifty and a half million tons of traffic have passed over 
them. 
Huge ingots are placed in soaking pits and forged direct by 
120-ton hammers, or pressed into shape by 14,000-ton presses. 
With such machinery the name of our late Member of Council, 
Benjamin Walker, will always be connected. 
There are steel castings, for parts of ships, that weigh over 35 
tons. We electrically rivet and electrically anneal hardened 
ship-plates that could not otherwise be drilled. Photomicro- 
graphy, originated by Sorby in 1864, now enables us to study 
the pathology of steel, and to suggest remedial measures for its 
treatment. Stead’s work in this field is already recognised as 
classical. Ewing and Rosenhain have, in a beautiful research, 
recognised quite recently by its aid that the plasticity of a 
metal is due to ‘‘slip” along the cleavage planes of crystals. 
Osmond also by its aid shows that the entire structure of certain 
alloys may be changed by heating to so low a temperature as 
225, C. 
Passing to questions bearing upon molecular activity, we are 
still confronted with the marvel that a few tenths per cent. of 
carbon is the main factor in determining the properties of steel. 
We are, therefore, still repeating the question, ‘* How does the 
carbon act ?”’ which was raised by Bergman at the end of the 
eighteenth century. Nevertheless, from the molecular point of 
view, much may be said in answer to the question. The 
mystery is in fact lessened now, as it is known that the mode of 
existence of carbon in iron follows the laws of ordinary saline 
solutions. Our knowledge is, however, of very recent origin, 
NO. 1541, VOL. 60] 
and we owe mainly to the Alloys Research Committee of the 
Institution of Mechanical Engineers the development of 
Matthiessen’s view that there is absolute parallelism of the 
solution of salt in water and carbon in iron. 
An ice-floe in a Polar sea contains a small percentage of 
salt ; a red-hot ingot of mild steel holds some two-tenths per 
cent. of carbon, but both the carbon and the salt are in the 
state of so/éd solution. If the ice had been cooled below— 18°C., 
it would entangle a solidified portion of salt water, which was 
the last part of the mass to remain fluid. So in the steel ingot, 
when it has cooled to the ordinary temperature, there is a 
solidified ‘* mother liquor” of carburised iron. We do not as 
yet know whether carbon is dissolved in fluid iron as carbon or 
as a carbide. We do know, however, that the presence of 0°5 
percent. of carbon in iron (such an amount as might occur in a 
steel rail) lowers the melting point of the iron from 1600°C. to 
1530 C. This lowering has enabled a calculation to be made, 
the result of which shows that the number of atoms in a molecule 
of carbon in fwd iron at this temperature is probably ¢wo. It can 
be shown that at a temperature of 800° C. the number of atoms 
in the molecule of carbon dissolved in so/éd iron is, in all pro- 
bability, ¢iree. At lower temperatures, the number of atoms is 
probably more than three. We metallurgists are not accustomed 
to think in atoms. Let me, therefore, represent such a three- 
atom molecule thus, without assuming how much 
iron is associated with the carbon. Following Bergman’s experi- 
mental method, but with the interval of more than a century 
separating his work from ours, we investigate the action of acids 
on carburised iron with a view to ascertain 
the nature of the atomic grouping of the 
carbon. 
In explaining this, I may adopt the ap- 
pended figure. It is most difficult even to 
attempt to make questions of atomic grouping | 
clear in a paragraph, but the figure will be @ @ 
helpful. To the historian it suggests vivid 
pages of Italian history, as the six spheres so 
arranged constitute the arms of the powerful 
family of Medici. To the chemist it is a precious symbol, 
and appeals to him as representing the carbon atoms 
as grouped in the benzene ring, The result of 
treating carburised iron with various acids is the 
formation of marsh-gas and more complicated organic com- 
pounds, of which propylene, acetylene, ethylene, and naphtha 
may be mentioned. Does the nature of these products help us 
to ascertain the number of the atoms in the carbon molecule as 
it exists in cold steel? I have consulted organic chemists, among 
whom I would specially mention my colleague Dr. Wynne, and 
their evidence is encouraging. The result of the action of 
powerful oxidising agents on certain forms of carbon is mellitic 
acid, C,(CO,H),, which is one of the benzene series, and this 
favours the view that solid carbon contains twelve, or some 
multiple of twelve, atoms in the molecule, But mellitic acid is 
graphically represented in the annexed diagram, the carbon 
CO_H 
ie 
pS 
co,4—C C-CO.H 
| | 
coH-C C-CO.H 
2 2 
SCs 
| 
CO.H 
atoms being arranged as the six spheres are in the arms of the 
Medici. The group CO,H is tacked on to each carbon sphere. 
From this it may be argued that the molecule of solid carbon 
consists or one or more carbon “rings.” In cold steel, the 
group of CO,H may be replaced by the group Fes, which is 
broken off by the action of suitable solvents leaving free carbon. 
Hence the six-atom carbon molecule may exist in steel. 
