44 
NALRORE 
[| NOVEMBER 8, 1906 
the first instance the constituent rich in zinc, whilst the 
constituent rich in copper assumed an electronegative posi- 
tion, acting, of course, as the kathode of the couple. 
But, when the eutectic had been transformed into spongy 
copper, the latter. assumed the electronegative position and 
the true brass became the anode, hence gradually trans- 
forming the whole mass from Muntz metal into spongy 
copper. In the case of the Prodano, the electrolyte was 
proved beyond all doubt to have consisted of fatty acids 
due to the use of improper lubricants. Little by little the 
brazed seam was cuprified until the junction became so 
weakened that at a pressure of only 130 lb. per square 
inch the port main steam-pipe opened for a space of 6 feet 
and consigned four men to an agonising death. 
This research, made at the Sheffield College under in- 
structions from the committee of Lloyd’s Register, resulted 
practically in the abolition of brazed copper main steam- 
pipes, and in the substitution of rolled steel ones. 
Reaching the third section of the lecture, this undoubtedly 
must be regarded in the steel age as the most important, 
since it dealt with steel. Taking the base of steel, namely, 
pure iron, this had a similar structure to that of pure gold, 
but the etching figures exhibiting the molecular orientation 
in the allotrimorphic crystals of this metal were seldom 
revealed by ordinary etching. 
Broadly speaking, iron was converted into steel by the 
addition of the element carbon, and researches made in the 
Sheffield College indicated that steels naturally divided 
themselves into three classes, mamely, unsaturated, 
saturated, and supersaturated steels. If 0-3 per cent. of 
carbon were added to steel, the carbon converted one-third 
of the iron into the constituent pearlite, and in such a 
steel, as cast, the iron or ferrite frequently arranged itself 
into a pattern, indicative of cubic crystallisation exactly 
comparable with the figures observed by Widmanstatten 
in the non-terrestrial steels called meteorites. In saturated 
steels, just sufficient carbon, approximately 0-9 per cent., 
had been added to the ferrite to convert it totally into the 
constituent pearlite, a definite mixture corresponding to 
the formula (21Fe+Fe,C). This definite mixture presented 
at least three well-marked phases having different 
mechanical properties determined by the state of the 
division of the carbide Fe,C. These phases might be 
differentiated by distinguishing the involved carbide as 
emulsified, normal, and laminated, the latter being the 
pearly constituent of Sorby, presenting a play of gorgeous 
colours, determined by the varying thickness of the laminz 
acting like mother-of-pearl in nature, or the interference 
grating in science. Through no scientific foresight, but, as 
a matter of fact, by an act of carelessness, there had been 
secured at the Sheffield College a section showing the trans- 
formation of pearlite into hardenite in the most perfect 
manner yet recorded. The two constituents, pearlite and 
hardenite, might humanly be described as the most 
important in nature, since upon unhardened and hardened 
steel depended the remarkable triumphs of the civil, the 
mechanical, and the electrical engineer. 
The quartz-hard transformation product of pearlite dis- 
covered by the versatile genius of Dr. Sorby itself pre- 
sented what might be termed effective and futile phases, 
dependent upon the temperature of quenching. In properly 
quenched steel, the accidental section before referred to 
showed that at a moderate temperature the transformation 
proceeded, not suddenly, but from a series of converging 
centres, until the whole mass consisted of the obsidian-like 
substance, structureless hardenite. At too high a tempera- 
ture this steely obsidian developed decisive cubic crystal- 
lisation, recorded in the micro-structure by equilateral 
etching figures indicative of ruined steel. In supersaturated 
steel in the unhardened condition, the cells of pearlite were 
environed by brilliant walls of cementite, Fe,C, which in 
hardened steel enveloped similar cells of hardenite, corre- 
sponding to the empirical formula Fe,,C. 
Of the three broad types of steel described, by far the 
most important was unsaturated steel, a synonymous term 
for which was structural steel, embracing boiler-plates, 
ship-plates, bridge-plates, rails, and the gigantic engine 
parts which formed the backbone of our battleships and 
cruisers. 
To show th> enormous importance of the scientific study 
of this class of steel, it was well to indicate, not only its 
NO. 1932. VOL. 75] 
failure, but after brilliant service, also that of the micro- 
scope scientifically applied. 
The figure thrown upon the sereen was that of a boiler, 
which might be described as several sorts of boiler. It 
was a marine boiler, a cruiser’s boiler, and possibly a mad 
boiler—it was, at any rate, cracked. Fortunately this 
rupture occurred before the cruiser was put into com- 
mission, and a defect in the steel which might have resulted 
in a catastrophe was detected by an extra inspection after 
the boiler had been impressed with the Government pass 
mark. The chronology of the testing operations was re- 
corded in the following table :-— 
Date Nature of pressure lb. per sq. in. 
February 5 ce Hydraulic 228 
ss 8 re 260 
” 19 oo ” see 395 
ye e20 oa Steam co 60 
cs .20 y Hydraulic 270 (burst) 
The mechanical tests of the boiler-plate steel which had 
thus failed left little to be desired, and the same remark 
applies to static mechanical tests taken along the line of 
fracture. Micrographic tests indicated that the steel pre- 
sented marked features of inferiority when compared with 
undoubtedly good boiler-plate steel. Superficially the matter 
was thus solved, but, under alternating or dynamic stress 
tests, slightly beyond the elastic limit, the steel registered 
tests varying from 230 to 1292 alternations. The most 
disconcerting feature in these astoundingly divergent tests 
was that the test bars registering them were identical in 
micrographiec structure. 
At the Cambridge meeting of the British Association, the 
lecturer suggested that these divergent tests must be 
associated with opposite sides of the plate subjected to 
varying heat treatment. The lecturer was quite wrong; 
and, after twenty-five years’ experience, had failed to realise 
the fact that in connection with steel one must often expect 
the unexpected. 
Remarkable failures in structural steel were commonly 
associated with the phenomenon called ‘‘ fatigue.’? What 
was “‘ fatigue’’? Some little time ago, in an important 
naval trial at the King’s Bench, counsel requested the 
lecturer to define for My Lord the meaning of this term, 
which had frequently occurred during the trial, and which 
he failed to understand. Unfortunately the lecturer also 
was involved in the outer darkness of My Lord on this 
matter, but was compelled to give ‘‘ fatigue ’’ at that time 
a definition, which remains substantially true to-day, 
namely, that he regarded ‘‘ fatigue’’ as a generic term 
used clearly to explain all cases of fracture which were 
not understood. Before venturing to suggest an explan- 
ation for these mysterious fractures, for which popular 
blame often fell upon men who were doing their very best, 
he would ask his hearers to imagine that that small cloud, 
no bigger than a man’s hand, now hovering over the North 
Sea, should burst in storm, and that our armour, our 
guns, and our armour-piercing shells should be put to the 
stern implacable test of actual warfare. 
guns were faulty, our shells failed to penetrate the armour 
of the enemy, our armour was incapable of protecting the 
gallant inmates of our battleships; assuming this hypo- 
thesis, which the lecturer believed to be totally untrue, 
what would all this mean? It would mean that the 
internal architecture of British wrought steel was all wrong, 
and the interesting question thus arose, who were the 
men responsible for the internal architecture of these 
metals? The lecturer knew them well. They were grave- 
eyed men with set mouths, who, week after week, month 
after month, and year after year, lived and moved, and 
had their being, and sometimes died. amid the flare of 
gigantic furnaces and the rattle of Titanic rolls, stead- 
fastly working upon those metals which formed Britain’s 
first line of defence, and to-night, on behalf of these in- 
articulate men, the lecturer confidently asked his dis- 
tinguished audience to exclaim in their hearts, “‘ These 
men have deserved well of their country.”’ 
Reverting to the remarkable and disconcerting fact that 
two pieces of the faulty boiler-plate steel of identical struc- 
ture, so far as could be seen by the microscope, gave 
astoundingly different results under dynamic stresses, the 
Supposing our . 
