858 Transactions of the American Institute. 



results accent and expression, since it is impossible to graduate the 

 force of these magnets. Pianists will never be supplanted by any 

 such self-moving device. 



The Terrace Furnace. 



This furnace, the invention of GastenhofFer, of Germany, has been 

 successfully used for several years at Swanzea, Wales, and lately in 

 Colorado, for burning the suljjhur in copper and iron pyrites. It 

 consists of a hollow vertical shaft, about twenty feet high, with an 

 area four feet by two inside, which contains a number of triangular 

 bars, made of fire-clay, about four inches wide and four inches apart, 

 60 arranged as to form a series of horizontal shelves alternately in 

 the same vertical line, and extending nearly to the bottom. Below 

 is a temporary fire-grate on Mdiich fuel is at first used to heat the fire- 

 clay shelves and the w^iole inside of the furnace. When this has 

 been accomplished the grate is withdrawn, and a stream of powdered 

 pyrites, containing at least sixteen per cent of sulphur, is then poured 

 in at the top of the furnace, and allowed to drop down from one 

 shelf to another ; at the same time just aii* enough is admitted at the 

 bottom to furnish oxygen to the burning sulphur. The combustion 

 of the sulphur produces heat enough to make the process continuous. 

 The gaseous products, principally sulphurous acid gas, are carried oft 

 into a leaden chamber, where by the ordinary method, sulphuric acid 

 is produced. One furnace at Swanzea ran sixteen months without 

 intermission ; and it is evident that, without interruption from break- 

 age or disarrangement of parts, the process may be carried on indefi- 

 nitely. This furnace is admirably adapted to the manufacture of 

 sulphuric acid, but it is not so valuable for the simple purification of 

 the metals in pyrites, because the high heat required for the complete 

 abstraction of the sulphur melts the pyi'ites too rapidly, and results 

 in [what is technically called " gumming up," which prevents the 

 powder from passing down the various shelves. 



The Gold Eegion of Nova Scotia. 



Dr. T. Sterry Hunt, in an ofiicial report lately printed by order 

 of the House of Commons of Canada, describes the geological forma- 

 tion of the auriferous fields of Nova Scotia, and the manner in which 

 gold has been obtained, from which we collect the folloM'ing informa- 

 tion. The coast district of Nova Scotia, which has become famous 

 for its gold, consists of a zone of ancient stratified rocks lying exposed 



