94 Mr. E. B. Poulton. On a special Colour-Relation [Feb. 10, 



Recapitulation of foregoing Experiment. 



10,675 lbs. leady bismutli, holding five per cent, lead, yielded 

 9306 lbs. of good commercial bismutli by the crystallization process, 

 or within six per cent, of the total contents of pure bismuth. 



Leaving for subsequent treatment — 



Of alloy, holding 40 per cent, of lead, 1188 lbs., which is equal to 

 11*13 per cent, of the whole weight of metal treated. 



Average Analysis of the Bismuth Ores worked upon. 



Bismuth 44" 5 7 



Lead 235 



Antimony 0*64 



Arsenic 1*26 



Molybdenum 5*02 



Tellurium 0*17 



Iron 525 



Manganese 0*05 



Copper 0-24 



Tungstic acid 2*45 



Alumina 0*18 



Magnesia 0-09 



Lime 0"81 



Carbonic acid 1*47 



Sulphur 3-77 



Insoluble earthy matter, chiefly silica 23'12 



Water 337 



Oxygen in combination and loss 5' 19 



100-00 



II. " An Inquiry into the Cause and Extent of a special Colour- 

 Relation between certain exposed Lepidopterous Pupae 

 and the Surfaces which immediately surround them." By 

 Edward B. Poulton, M.A., of Jesus and Keble Colleges, 

 Oxford, Lecturer in Zoology and Comparative Anatomy 

 at St. Mary's Hospital, Paddington. Communicated by 

 Professor E. Ray Lankester, F.R.S. Received Feb- 

 ruary 10, 1887. 



(Abstract.) 



Historical. — Mr. T. W. Wood first called attention to the colour- 

 relation in pupae (' Entom. Soc. Proc.,' 1867, p. xcix), adducing 



