50 
MESSRS. C. T. HEYCOCK AND F. K. NEVILLE ON 
B’rom 10 to 13’61 atoms of tin, iiioliisive, it was noticed that a salt precipitate began 
to form on the walls of the crucible at the moment of reading the freezing point and 
rapidly increased. 
At 12‘r)5 atoms the freezing point was indicated, not by a period of stationary 
temperature, but by a sudden marked decrease in the rate of cooling. 
At 14'4l atoms, in spite of copious precipitate, stirring was quite easy for several 
degrees below the freezing point. This point was distinctly indicated. 
At 15 atoms, readings A and B, different freezing points for the same alloy, 
correspond to different ijhenomena. At A there was little precipitate; B was a 
much steadier temperature, with abundant precipitate of a finely gritty character. 
At this momenf. the alloy felt to the stirrer like a mixture of sand and water. 
The reading at 15‘57 atoms, or just below it, resembled B. 
from 16T5 atoms onwards the freezing points are very steady temperatures, quite 
different in character from the preceding, except B. 
0 and D correspond to different phenomena, D being so constant as to resemble a 
eutectic point. At D the alloy sets to a solid mass without a further fall in 
temperature. 
Table VIIb.— Freezing Points of Alloys made by adding Cojjper to Tin. 
200 (jraiiia Tin. 
(1.) 
'total \vei”ljt 
of copper present. 
(3.) 
.Percentage of 
copper. 
(3.) 
Atomic 
jiercejitage of 
copper. 
(4.J 
Freezing jioiiit on 
the Centig-racle 
scale. 
(5.) 
Atomic fall. 
0 
n 
0 
232-32 
1-UU6 
-5U 
-93 
229-69 
2-93 
1-854 
-92 
1-70 
(227-7S) 
5-029 
2-45 
4*48 
(227-77 J 
1 
« 
262-60 
lU-50 
4-99 
8-92 
364-4 
1 
21-32 
9-63 
16-39 
433-1 
36-82 
15-55 
25-57 
496-3 
46-85 
18-98 
30-42 
521-2 
The freezing point of the pure tin was marked by surfusion. 
The atomic fall for copper in tin, 2 93°, is identical with that obtained by us in 
1889 with a mercury thermometer (‘Chem. 8oc. Jour.,’ 1890, p. 392). 
The readings at 1'7 and 4‘48 atoms of cojiper give the freezing point of the eutectic 
alloy of tin and cojiper. 
