158 KEPORT OF NATIONAL MUSEUM, 1887. 



Accretions, which are deposits formed upon the walls of the furnaces ; 

 these are assorted according to their characteristics, and then go back 

 to the shaft furnaces. 



The bullion from these furnaces holds a high position with the re- 

 fineries on account of its freedom from impurities, due to the purity of 

 the ores of the Madonna mine, which form a large proportion of the 

 charge in the shaft furnaces. It varies in richness, although it gen- 

 erally carries 300 ounces of silver per ton, and about an ounce of gold. 

 It is cast into bars or pigs weighing 98 pounds, and is shipped from the 

 furnace in car-loads of 300 bars. 



By far the greater number of accessions are specimens sent in for 

 examination and report, 80 reports, covering 186 specimens, having 

 been made. 



In cataloguing the collection, 671 entries, covering 1,266 specimens, 

 having been made, and during the year 1,358 cards added to the cata- 

 logue ; 1,840 labels have been written ; 14 boxes of duplicates and 

 reserve material have been sent to general storage; 242 specimens have 

 been sent out in exchange. 



The total number of specimens in the collection is about 49,000, of 

 which 18,000 are on exhibition, 12,000 are duplicates, 7,000 reserves, 

 the balance consisting of specimens as yet unadministered upon, and 

 which are at present classed with the reserve series. 



