120 MR. F. C. CALVERT AND MR, R. JOHNSON 
a el 
| 
| Calculated 
Formule of Alloys and per centages of each. | enlisted. Cast Hon Cast Iron 
phe ee | 
NOE eye "300 6450 | 6083 
Zactie sey Oe eh ie 330 6875 | 82°70 
SER acy Neamt 400 83:33 | 110-00 
Se a eee 450 9370 | 12458 
Be Zing | oe ease tee 505 | 10520 | 131-22 
Zn ea tid ane 600 | 125-00 | 142-08 
BZ ae ee 580 | 12083 | 15838 
These results show that these metals exert no action on 
each other, as the numbers indicating the degrees of hard- 
ness of their alloys are rather less than those required 
by theory. Our researches on the conductibility of heat 
by the three above series of alloys throw, we believe, some 
light on the great difference which the alloys of bronze 
present as compared with those of tin and zinc; for we 
have stated above that the latter conduct heat as a mix- 
ture of metals would do, and not as the former series, 
which conduct heat as definite chemical compounds. 
We shall conclude by giving the degrees of hardness of 
two other series of alloys, viz., those composed of lead and 
antimony, and lead and tin. In the series of lead and 
tin we find that tin also increases the hardness of lead, 
but not in the same degree as it does that of copper. 
