92 



Mr. E. Matthey. 



[Feb. 10, 



myself to the separation of lead, the presence of which especially 

 presented at first great difficulties. 



As stated above, I have found that I can separate one by one the 

 metals mentioned above, all of which have been associated with crude 

 bismuth which has come under my notice. In this, success though 

 gradual, has been complete : but I was still confronted by the fact 

 that the lead alloy was retained by the bismuth with a most charac- 

 teristic persistency which seemed to defy all efforts of separation 

 excepting by tedious wet or acid processes. 



The amount of lead existing in the bismuth I operated upon, after 

 freeing it by dry processes from its other impurities, varied from 2 to 

 10 per cent. 



Bearing in mind the respective fusing points of lead and bismuth, 

 it occurred to me that, as alloys of bismuth and lead fuse at a 

 temperature considerably lower than that of bismuth itself, separation 

 would possibly take place between the two metals at a certain point 

 of cooling ; I therefore made the following experiment : — 



Taking a quantity of bismuth (about 10 cwt.), -holding 11*5 per 

 cent, of lead, and fusing same, I allowed the metal to cool until the 

 major part of it had crystallised, then removing the fluid portion. 



The residue showed by assay only 6*35 per cent, of lead, pointing 

 at once to the partial separation I had hoped for. 



These crystals again similarly treated showed only 3*75 per cent, 

 of lead. 



The operation repeated gave crystals with only 2 per cent, of lead, 

 and a fourth crystallisation brought this down to below 0'5 per cent. 



As a matter of possible interest, I subjoin the progressive results 

 during the crystallising operations of several lots up to the point of 

 bulking, and of finally separating every trace of lead : — 



Bismuth holding 14'6 per cent. Lead. 



1st crystallisation gave crystals holding 9*8 per cent, of lead. 

 2nd ,, ,, ,, 5*1 „ ,, 



3rd ,, ,, „ 3'8 „ „ 



4th „ „ „ 2-5 ,, „ 



5th ,, ,, ,, 0'4 ,, ,, 



Bismuth holding 12 per cent. Lead. 



1st crystallisation gave crystals holding 6*2 per cent, of lead. 



2nd „ „ „ 4-2 „ 



3rd ,, ,, ,, 1*4 



4th „ „ „ 0-4 „ „ 



