THE APPLICATIONS OF EXPLOSIVES. 



303 



Gi;npowi)j;r Grains. The large ones are over 

 five pounds weight, each. 



The material employed is cotton, but whether fresh from the 

 field or in the form of waste, it must first be freed from dirt by 

 hand picking and sorting, 

 and from grease and in- 

 crusting substances by boil- 

 ing in a weak soda solution. 

 The cotton is now dried by 

 wringing in a centrifugal 

 wringer and exposing to a 

 current of hot air in a metal 

 closet; but as the compacted 



mass of cotton holds moisture with great persistency, after partial 

 drying the cotton is passed through a cotton picker to open the 

 fiber, so that it not only yields its contained water more readily 

 and completely, but it also absorbs the acids more speedily in the 

 dipping process to which it is subsequently exposed. 



When the moisture, by the final drying, is reduced to one half 

 of one per cent the cotton is, while hot, placed in copper tanks 

 which close hermetically, where it cools to the atmospheric tem- 

 perature and in which it is transported to the dipping room, where 

 a battery of large iron troughs, filled with a mixture of one part of 

 the most concentrated nitric acid and three parts of the most con- 

 centrated sulphuric acid, set in a large iron water bath to keep the 

 mixture at a uniform temperature, is placed under a hood against 

 the wall. The fluffy cotton, in one-pound lots, is dipped handful 

 by handful under the acid, by means of an iron fork, where it is 

 allowed to remain for ten minutes, when it is raised to the grating 

 at the rear of the trough and squeezed with the lever press to re- 



BuRNiNQ Disk of Gun Cotton. 



EXTINGI ISHINO BURNING GuN CoTTON. 



move the excess of acid. It still retains about ten pounds of the 

 acid mixture, and in this condition is placed in an acid-proof stone- 

 ware crock, where it is squeezed by another iron press to cause the 

 contained acid to rise above the surface of the partly converted 



