48 
MESSRS. C. T. HEYCOOK AND F. H. NEVILLE ON 
The freezing’ points from 2()'53 to 24’32 inclusive were noted as being so steady as 
to resemble eutectic points. This is the region from SnCu^, to SnCug. 
At 24’32 atoms no precipitate was noticed at the moment of reading the freezing- 
point, but before the metal had cooled two degrees below the recorded temperature 
stirring had become impossible ; in fact, this alloy may be said to solidify at a 
constant temperature. 
At 25‘35 atoms, that is, with more tin than corresponds to SnCug, we begin 
again to notice an abundant precipitate at the moment of reading the freezing point. 
After the first reading at 26’96 atoms of tin a portion of the alloy was removed 
from the crucible. This alloy was white, hard, and brittle, with a conchoidal 
fracture. 
At 30’51 atoms the freezing point was not so well marked as hitherto. There was 
much ]Drecipitate soon after the reading. 
A.t 34’57 atoms of tin surfusion was noticed at the freezing point. 
From here onwards, as we add more tin, the pause in the cooling, which marks the 
freezing point, hecomes less and less marked, but up to 64'2 atoms of tin there is no 
dilhculty in determining the freezing point. There is now no precipitate observed 
at the moment of reading the freezing point, or for some time aftei'wards. 
Table VIIa. — Freezing Points of Alloy made hy adding Tin to Copper. 
Series 2.—200 grams Electrolytic Copper. 
(!•) 
Total weight of 
Hn present. 
(2.) 
Percentage of 
tin. 
(3.) 
Atomic 
percentage of tin. 
(4.) 
Freezing point "on 
the Centigrade 
scale. 
(5.) 
Atomic fall. 
0 
0 
0 - n 
1081-0 
G-046 
2-93 
1-9.54 
1062-3 
11-73 
37-07 
15-G4 
9-04 
944-8 
15-07 
G7-08 
2.5-12 
15-24 
797-9 
A 
11 
11 
793-1 
B 
83-lG 
29-37 
18-23 
762-8 
The points A and B are two well-marked freezing points of the same alloy, the 
lower temperature B corresponding to some eutectic state (see Curves). 
F’or the ]nir]^ose of drawing the curve, in order to bring tliis series into agreement 
with Series 1, one degree was added to the first reading given above, and proportional 
amounts to thf^ lower re.a.fhngs. 
