26i Mr. Daniell on a New Register-Pifrometer 



corded, it may be seen, in Table XIV. of the expansion of 

 the alloys, that a composition of half copper and half zinc 

 presents the same anomaly; the expansion for the 600° to 

 boiling mercury is not quite four times that of the 150° to 

 boiling water. In the alloy of three fourths copper to one 

 fourth zinc, the rate of expansion increases in a small degree; 

 and in common brass, where the proportion of zinc is still less, 

 it increases still more rapidly. 



My purpose in instituting these experiments upon the al- 

 loys, was to observe the relation which might exist between 

 the expansions of the pure metals and those of their mixtures; 

 and the better to illustrate any such, I made alloys of copper 

 with known multiple proportions of zinc and tin. I shall here 

 present, in a tabular form, the temperatures of their melting 

 points, as derived from their expansions to the boiling points 

 of water and mercury; as, although I am not able to compare 

 them with results directly obtained by immersion, we can 

 judge, by comparison with the similar calculation of the pure 

 metals, within what limits any error is probably confined. 



Table XVI. 



Fusing Points of Alloys, derived from their Expansions to 212° 

 and 662° supposed equable. 



I have not included in the foregoing Table the alloy of half 

 copper and half tin, but have exhibited its expansion to the 

 boiling point of mercury in Table XIV. This mixture was 

 very hard and brittle, and resembled the speculum metal of 

 reflecting telescopes. After it had been exposed to boiling 

 mercury, it appeared as if it had undergone partial fusion ; it 

 was set fast in the cavity of the register, and had thickened 

 towards the lower extremity. I am inclined to think that it 

 had nearly attained its melting point, but it was broken in re- 

 moving it; and I had not an opportunity of trying any further 

 experiment with it. 



With regard to these alloys, the experiments are not nu- 



M 



