302 
NATURE 
Feb. 8, 1883 
striking and elegant experiments, performed with the simplest | governed by three conditions : 
(1) the temperature of the blast; 
apparatus, may be considered, in its result, as the complement | (2) that of the escaping gases ; (3) the quantity of carbon which 
of Prof. Abel’s. The latter goes to show that in soft steel the car- 
bon is present as a chemical compound, which is dissolved by hard- 
ening ; the former, that in hard steel the carbon is present as an 
alloy, varying with the temper. Between the two, we seem to 
reach the threshold of a complete theory. They approach the 
subject, however, from different sides, Prof. Hughes's work being 
purely electrical, Prof. Abel’s purely chemical; and this makes 
their convergence the more important. Finding that the induc- 
tion balance was equally sensitive to molecular and to chemical 
changes, in the metals tested, Prof. Hughes set himself to devise 
an instrument by which to examine the former class of pheno- 
mena by themselves. A wire forming the core of an ordinary 
magnetic coil, and capable of being shifted, twisted, &c., as 
desired, supplies what he requires. The coil is joined to a 
galvanometer, or, better still, to a telephone; the wire is joined 
to a battery, and currents are sent through it. So long as the 
wire is at right angles to the coil, no effect is produced ; but if 
we set it at an angle to the coil, sounds are instantly heard, 
betokening the presence of induced currents in the coil. This is 
the ordinary effect of electro-magnetic induction, as discovered 
by Faraday. Now, instead of shifting the wire, let us give it a | 
slight twist, say of 4o°: the sounds are instantly heard as before, 
and we detect induced currents, which are positive for right-hand 
torsion, negative for left-hand torsion. Prof. Hughes’s explanation 
of this is that the molecules of the wire, which he regards as so 
many separate magnets, have been given a twist round the axis, 
and thus set at an angle to the coil, just as the whole wire was 
by the shifting in the first case. Now let us twist the wire still 
further, even to several complete turns, No greater strength of 
current is observed, showing that the angle once given to the 
molecules is not exceeded, and that the subsequent torsion is of 
the wire asa whole. Approach to the wire, thus twisted, one 
pole of a natural magnet, laid parallel to the wire: the sounds 
cease, indicating that the ma-netism has spun the molecules 
back again into their original directions. Approach the magnet 
at right angles to the wire: the current returns to zero while it 
is still two inches distant, and when it is in contact there is a 
reversed current, whith is then at its maximum. Lastly, 
removing the magnet, untwist the wire by some 40°: the current 
returns to zero, showing that the molecular torsion has disap- 
peared, while the molar torsion remains almost the same as 
before. 
Tn all these effects the wire has been supposed to be of soft 
iron: a remarkable difference appears when we turn to tempered 
steel. For we now fail to detect more than slight traces of 
molecular disturbance or rotation, no matter how many turns we 
give to the wire. Thus, whereas in the iron we appear to have 
great molecular freedom, with steel we have almost complete 
molecular rigidity. But this molecular rigidity is found to obtain 
also in all alloys of steel which have been tested—e.g. magnetic 
oxide, iron and sulphur, iron and tungsten, &c. Hence we draw 
the conclusion that tempered steel is likewise an alloy, the 
associated elements in this case being, of course, iron and 
carbon, 
The above is the essential part of this striking paper ; but 
the same idea of molecular freedom and rigidity was illu-trated 
by other examples, Thus, if a tube nearly filled with iron filings 
be magnetised, the magnetism, though permanent so long as the 
tube is still, is removed in an instant by shaking, or even by 
turning the tube gently, so that the filings roll over each other, 
If, however, we pour in any viscous liquid, ‘he magnetism can 
indeed be imparted, but it cannot be mechanically removed : the 
filings are no longer able to revolve back into their former posi- 
tions. Again, we may magnetise an iron and a steel wire to the 
same degree, and then give each a slight pull to set it in vibra- 
tion ; it will be found that almost the whole of the magnetism 
has disappeared in the iron, while it is scarcely affected in the 
steel. By such illustrations the remarkable physical dinerences 
thus shown to exist between iron and steel were brought very 
clearly bome to the audience ; and whether they accepted or not 
the theoretical explanation, they could not fail to recognise the 
Peeetise and fractical character of the facts thus put before 
them. 
The third paper on the list, by Mr. Chas. Cochrane, was a 
sequel to one read by the same author at the Leeds meeting of 
the Institution, and dealt with Blast-Furnace working, with 
special reference to the analysis of the escaping gases. It was 
Jaid down at the out:et that economy of fuel in blast-furnaces is 
can be maintained in the condition, once attained, of carbonic 
acid, instead of being re-transformed into carbonic oxide by 
absorption of carbon in the fuel. On the first two of these heads 
there is, of course, nothing new to be said; but they were 
illustrated by elaborate and valuable tables, giving, in units of 
fuel (C burnt to CO), (a) the heat carried zz by blast of a given 
weight and temperature, (4) the heat carried owt by escaping 
gases of given weight and temperature. The third is dwelt on 
at some length; and tables are given, showing, for any given 
consumption of C per ton of pig, the ratio of CO, to CO in the 
escaping gases, first when all the CO,, once formed, is retained in 
that condition ; and afterwards when 3 cwt., I cwt., 14 ewt., 
&c., are afterwards reconyerted into CO, or, as the author terms 
it, when a ¢ransfer of  cwt., I cwt., &c., of C has taken place. 
From this is deduced the conclusion that the mere knowledge of 
the ratio of CO, to CO in the escaping gases, as given by 
analysis, is useless to indicate what is really going on in the 
furnace; because the same ratio may appertain to any different 
conditions, according to the amount of the transfer which has 
taken place, from CO, back to CO. If, however, the consump- 
tion of carbon per ton of pig-iron has been at the same time 
ascertained, then we are at once able to refer the case to its 
proper position ; and the knowledge of the ratio between the two 
cases enables us at once to see what amount of transfer has been 
going on, and what rrospect there is of effecting an improve- 
ment. It was further pointed out that the main causes of this 
injurious re-conversion of CO, into CO were (1) the fact that 
the limestone, used as flux, contains a proportion of CO,, which 
can only be evolved at a red heat, and therefore in contact with 
red-hot coke, which immediately gives up some of its C to the 
evolved gases ; (2) the fact that the ore, especially in the larger 
pieces, does not get completely de-oxidised until it reaches the 
red-hot region, where the CO ascending in the furnace first 
unites with the oxygen in the ore to form CO,, and then absorbs 
another equivalent of C from the coke, so returning again to 
the condition of CO. It is therefore suggested that both these 
sources of evil might be removed if (1) the limestone were ca/- 
cined before entering the furnace, so as to have already parted 
with its oxygen, (2) the ironstone were broken up into pieces 
small enough to insure their decomposition in the higher parts of 
the furnace. Another means of accomplishing the latter result 
was to increase still further, if necessary, the height of furnaces. 
A sanguine estimate was made of the economy that would 
attend the application of these two devices, which it was 
expected might reach over 3 cwt. of coke per ton of pig-iron 
made, 
The value to ironmasters of the elaborate tables annexed to 
the paper, and of the mode in which the problem of blast- 
furnace economy is presented, cannot but be very great; but 
grave doubts were expressed in the discussion, by Mr. I. 
Lowthian Bell, F.R.S., whether the practical results would 
answer the author’s expectations. As regards the use of cal- 
cined limestone, in particular, it was stated that it had already 
been tried, without effecting any economy, at least in large 
furnaces ; the suggested reason being that the calcined lime, as 
soon as charged, re-absorbed CO, from the escaping gases, and 
that although heat was no doubt disengaged in the process, 
yet this was too near the throat of the furnace to have any 
serious effect. Moreover it is to be remembered that the 
previous calcining of the limestone must itself require fuel, the 
amount of which must be deducted from any apparent gain due 
to the absence of CO, in the lime within the furnace. 
The fourth and last paper which was read (one on Screw 
Shafts, by Prof. Greenhill, of Woolwich, being postponed for 
want of time) was by a Swiss engineer, Herr Wendelstein of 
Lucerne, and gave a good and clear account of the mechanical 
arrangements connected with the construction of the great tunnel 
under the St. Gothard, the longest in the world. These are 
beyond our scope ; and the important questions of temperature 
and ventilation, though just touched upon, were reserved for a 
future communication, which will also deal with the railway 
approaches. It may be mentioned that the observations of Dr. 
Stapff, the official geologist at the St. Gothard, were stated to 
give as the rate of increase of heat in that locality, 2° C. per 100 
metres depth (1°1 Fahr. per roo feet) ; and that, if this figure be 
applied to the Simplon tunnel, as at present proposed to be 
made just above Brieg, the heat to be dealt with would reach the 
very high figure of 47° C., or 116° Fabr. 
