L. MECHANICS AND ENGINEERING. 523 



to twenty per cent, of water, and, consequently, incombusti- 

 ble under ordinary circumstances, can be exploded by deto- 

 nating fuses almost as well as if perfectly dry, and it may be 

 kept quite damp for an indefinite period of time without af- 

 fecting its utility. In the course of his experiments, Mr. Brown 

 placed disks of wet compressed gun-cotton upon a slab of 

 iron an inch thick, without any covering, and on exploding 

 them the iron was found deeply indented. A solid tamping 

 of sand was then laid over the disks, and after the explosion 

 the iron was shattered to fragments. By this new discovery 

 the cotton may be kept w^et in cylinders, and will be abso- 

 lutely free from any dangerous results should it be exposed 

 to any agency other than that of a percussion-cap or a deto- 

 nating fuse. New York Herald, December 30, 1872. 



DIKECT METHODS FOE THE MANUFACTUKE OF MALLEABLE 



IKOX. 



Von Tunner, in an article on the manufacture of malleable 

 iron from the ore, remarks that the mechanical puddling 

 method of Dank has given a fresh impetus to efforts in this 

 direction, since by this process six to seven per cent, more 

 iron is obtained than the amount of cast iron introduced, so 

 that, allowing for waste, twelve to fourteen per cent, of iron 

 must result from the ore added; or, according to Dank's 

 statement, about one half of its iron. The reduction of the ore 

 is doubtless mainly due to the carbon dissolved in the molt- 

 en iron coming into most intimate contact with the ore, also 

 for the most part in a fluid condition. The conversion of this 

 secondary direct manufacture of malleable iron into the chief 

 feature of the process, suggested itself very naturally, and 

 has been much discussed. Siemens has stated that it would 

 be difficult to obtain such a temperature, in a rotary hearth, 

 as would fuse five to six tons of pure iron, and that it would 

 be impossible to obtain fluid steel in it, since it w^ould at 

 once be deprived of its carbon by contact w^th the walls of 

 ore of the furnace; but he remarked, at the same time, that 

 he had directed his attention long ago to the use of rotary 

 apparatus, not for puddling, but for the reduction of ores, and 

 hoped soon to give an account of his experience. It was the 

 opinion of Snelus, who has thoroughly investigated the chem- 

 istry of Dank's mechanical puddling, that it is impossible to 



