48 REPORT OF NATIONAL MUSEUM, 1889. 



Chromium is represented by specimens of chroinite from all the prin- 

 cipal locations in the United States and many foreign sources. 



Bismuth is represented by 2 specimens. 



The mineralogy and ores of aluminum are illustrated by 10 specimens 

 of cryolite, corundum, and beauxite. 



The extraction of aluminum by the Erizinuth process is illustrated 

 by 20 specimens, and its application by 22 specimens, metallic alu- 

 minum and its alloys, as prepared by the Pittsburgh Reduction Com- 

 pany. 



The mineralogy and ores of mercury are illustrated by some 40 speci- 

 mens from domestic and foreign sources ; 13 specimens are added to 

 illustrate the mine and works at New Almaden, California. 



Under the head of the general use of metals is shown a large series 

 of alloys described by Mr. Pearce in the Transactions American Insti- 

 tute of Mining Engineers, Vol. xiii, p. 738, and illustrated by 12 speci- 

 mens; the manufacture and utilization of brass, by 28 specimens; that 

 of soft alloys, babbitts, solders, etc., by 41 specimens; and that of type 

 metal, by 17 specimens. Welsh tin plate is represented by 15 speci- 

 mens. 



B. — NON-METALLIC MINERALS. 



These are illustrated as follows : 



Sulphur by 10 specimens, and the manufacture of sulphuric acid by 

 5 specimens. 



Abrading and polishing materials are shown by a fine large series of 

 some 200 specimens novaculites, schists, and sandstones in the rough 

 and finished state for sharpening edge tools.* Two columns of grind- 

 stone as prepared by J. B. Mitchell of Philadelphia may be noted here. 

 Each column stands some 7 feet in height, oue composed of 9 and the 

 other 13 varieties of grindstones, laid flat, one on another. The stones 

 are cut to a scale, being 12 inches in diameter, and each 2 inches of 

 thickness representing a diameter of 12 inches in the finished stone as 

 actually used. That is to say, stones which in the column are 12 inches 

 thick are for actual use made 6 feet in diameter, the thickness remaiu- 

 iug the same. All principal varieties both foreign and domestic now in 

 use in the United States are represented. The exhibit further com- 

 prises 40 specimens corundum and emery both in lumps and in pulver- 

 ized form, commercial sizes; 10 specimens of quartz for sandpaper ; 5 

 specimens tripoli ; 5 specimens infusorial earth ; 15 specimens pumice, 

 in the rock form, pulverized, and as fine dust, the product of explosive 

 volcanic action ; and 29 specimens illustrating the manufacture of em- 

 ery and sandpaper. 



The occurrence of asbestus is shown by a large collection comprising 

 some GO specimens from world-wide localities. The application of as- 



*Mainly the gift of the Pike Manufacturing Company of Pike Station, New Hamp- 

 shire. 



