38 
MESSRS. C. T. HEYCOCK AND F. H. NEVILLE ON 
For tlie first 5 atomic per cents, of lead there was an abundant precipitate at the 
moment of reading. After this concentration the precipitate at the moment of 
reading gradually became less and less, and before 45 atomic per cents, it ceased 
to be possible to detect precijjitate at the moment of reading or for some time 
afterwards. At this concentration plenty of precipitate could be felt on the bottom 
of the crucible when the alloy had cooled 50 or 100 degrees below the F.P. 
At 45 atomic per cents, of lead the alloy was allowed to cool to the eutectic 
point, but stirring had become impossible long before the temperature had fallen to 
this point. 
Beyond 50 atomic per cents, of lead the F.P. is only indicated by a slight decrease 
in the rate of cooling. 
At 34’32 atomic per cents, and at 53‘3 atomic per cents, the crucible had become 
too full and a portion of the alloy was removed. It will be noticed that the F.P. 
before and after this removal of a part of the alloy is substantially the same. 
At the. end of the experiments the solidified ingot of alloy was found to weigh 
389’8 grams, while from the weights of the two metals used it should have weighed 
392‘7 grams; part of this loss is due to metal adhering to the pyrometer and the 
crucible. 
Oxidation did not occur either during the experiments or during the cooling. 
