Proceedings of the Polytechnic Association. 707 



ISTew Fcexace for KoASTmG Oees. 



Mr. Yivian read a paper describing his improvement in furnaces 

 for roasting p)n'ite3 and other ores. The inventor claimed that his 

 furnace possessed several important advantages over those commonly 

 in use. 



Estimated Weight of Minerals. 



Dr. Lewis Feuchtwanger.— Frequent inquiries from persons inte- 

 rested in the sale of mineral lands induced the author to calculate 

 and combine tables, which he thinks will prove of great service. If 

 the purchaser of a clay, ochre, or coal bed, or of an iron ore deposit, 

 either pyritic, magnetic, spathic, specular or hematite, blende, 

 Franklinite, copper ores of the various grades, or galena or any other 

 mineral found in nature, would ascertain the extent of the vein, and. 

 calculate into cubic feet, he must find the weight of a cubic foot. 



It is known that 1,728 inches comprise one cubic foot, and that 

 one cubic foot of water weighs at a temperature of sixty degrees 

 Fahrenlieit, sixty -two and a half pounds avoirdupois. By ascertain- 

 ing the specific gravity of say lead, copper or iron, and multiplying 

 with sixty-two and a half pounds, the exact weight of one cubic foot 

 of these ores is obtained ; it may also be easily ascertained how many 

 cubic feet are contained in a ton of many substances ; for instance, 

 it is known that one ton of sand contains twenty-three and a half 

 cubic feet, and a ton of marble or granite ten and a half cubic feet ; 

 and by these means we can also find out the capacity of certain 

 mineral lands. 



Although the author's first intention was to begin with the most 

 common minerals or ores used for producing metals, such as galena, 

 blende, copper pyrites, etc., on reflection it was thought best to 

 arrange all substances the relative weight of each cubic foot of which 

 is to be ascertained in alphabetical order : 



Pounds 

 Avoirdupois. 



Anthracite coal has a specific gravity of 1.5 ; and a cubic foot 

 weighs 94: 



Antimonial copper, also called tetrahedrite or gray copper, from 

 many localities in the United States, has a specific gravity of 

 5.0, and a cubic foot weighs 300 



Antimonial silver, a mineral found abundantly in Mexico, IN^eva- 

 da, Hungary, etc., has a specific gravity of 9.5, and a cubic 

 foot weighs . 600 



Antimony ore, the gray sulphuret, generally called the crude 

 antimony, the substance used for producing the regulus, has a 

 specific gravity of 4.5, and a cubic foot weighs 279 



