96 DR. JOULE 0]Sr SOME THERMO-DT]S^A3IIC PEOPEE.TIES OF SOLIDS. 
excellence of the latter metal might be tested by ascertammg the amount of change m 
thermo-electric condition which can be produced by the process of hardening. 
15, The different varieties of cast iron I have tried present a sui-piusing range ot 
thermo-electric intensities, extending almost from that of wrought iron on the one hand, 
to that of German silver on the other. By the kindness of Professor F. C. Calvert. I 
have been enabled to examine several interesting specimens, of which he has furnished 
me with the analysis. The general conclusion arrived at is, that the metal is brought 
nearer bismuth as the quantity of carbon in combination is increased, but much more 
so than would be the case if cast iron exhibited merely the combmation of thenno- 
electric intensities which carbon and iron separately possess, at least if the mtensity 
generally assigned to carbon is correct. The intensity of the junction wi’ought iron 
and highly carbonized cast iron is as much as one-fifth of the intensity of antimony and 
bismuth. 
Thermo-electric Intensities of Metals, Alloys, &c. 
16. In constructing the following Table, I employed the thermo-multiplier already 
described, furnished with a variable extra resistance. I examined fii'st those metals 
whose thermo-electric qualities were most widely separated, and then those which lay 
intermediate and differed less from each other. Small arcs of deflection were observed, 
so that the deviation of the needle was a sufficiently correct measui-e of the mtensity ot 
the current, and constantly repeated comparisons were made with a standard ^ thermo- 
electric junction of copper and iron included in the same circuit with the junctions 
experimented on. 
17. Scale of Thermo-Electric Intensities at 12° Centigrade. 
Antimony, specimen of commercial 
Antimony, pure, prepared by Mr. Calvert 
Antimony, pure, prepared by Mr. Calvert, not well annealed 
Alloy consisting of 5 equivalents of antimony -+-1 equivalent of bismuth . . 
Alloy consisting of 4 equivalents of antimony -f-l equivalent of bismuth . . 
Alloy consisting of 3 equivalents of antimony -j-1 equivalent of bismuth 
Alloy consisting of 2 equivalents of antimony +1 equivalent of bismuth . . 
Alloy consisting of 1 equivalent of antimony -f-l equivalent of bismuth . . 
Iron, thick wire. Professor Calvert’s 
Iron, thin wire 
Iron, thick wire, very well annealed 
Iron, thick wire, hardened by plunging at bright red into water 
*Iron (Professor Calvert’s No. 1) drami into wffie 
firon (Professor Calvert’s No. 1) after puddling, but previous to being drawm 
into wire 
Jlron (Professor Calvert’s No. 1), cast, previous to puddling 
100 
98-06 
95-95 
83-75 
80-50 
78- 94 
68-70 
45-51 
80- 
79- 24 
78-24 
77-62 
76-00 
.65-21 
