L. MECHANICS AND ENGINEERING. 515 



fuel Mr. Siemens' furnace has been successfully applied to the 

 jjroduction of iron and steel, directly from the ore, and to pot- 

 teries and zinc-works, as well as to other branches of manu- 

 facture. 



In cases where the manufactories are situated in the vi- 

 cinity of peat bogs, it is proposed to produce the gas from the 

 peat directly on the sjDOt, and to convey it in pipes to the 

 places where it is needed. The essential principle of Siemens' 

 furnace consists in first converting the fuel, peat, or what- 

 ever else it may be, into combustible gas, in a separate cham- 

 ber of peculiar construction, and conducting it into the fur- 

 nace containing the material to be heated, to be then burned 

 with hot air. After use, the intensely heated products of 

 combustion are made to pass through brick chambers called 

 "regenerators," and the heat which would otherwise be wasted 

 is caught, stored up in the bricks, and subsequently used to 

 raise the air needed in the operation to a very high temper- 

 ature. 3 A, Ajjril 5, 1873, 358. 



NEW METHOD FOE TESTING THE QUALITY OP IRON. 



Van Ruth, the inspector of mines, of Holland, examines the 

 structure of iron by smoothing the surface at the desired 

 point, and then treating it from six to twenty-four hours, 

 according to temperature, etc., with hydrochloric acid, until 

 the slaggy portions, which are more readily afiected than the 

 iron, are dissolved out and the fibres are left in relief, so that 

 an impression may be taken from the surface with printers' 

 ink, India ink, etc., which will exhibit the structure clearly, 

 and serve for distinguishing and comparing the iron. 9 C, 

 J)ecember, 1812, 182. 



NEW PRESERVATIVE OF WOOD. 



The application of parafiine to the preservation of railroad 

 ties, by boiling them in it or coating them with it, according 

 to Hock, of Mariabrunn, is not effective ; but he suggests that 

 impregnation of dried w^ood by parafiine in solution, draining 

 off the excess of liquid, and distilling off the last portions of 

 the solvent at a high temperature, would be efficacious, by 

 leaving the paraffine in the pores of the wood in a finely di- 

 vided condition, which, on fusion, would form a highly pro- 

 tective coating. Ties treated in this way would probably be 



