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POPULAR SCIENCE MONTHLY. 



cotton. The covered crock is now placed with others in wooden 

 troughs containing running water so as to keep the temperature 

 uniform, where the cotton is allowed to digest for about twenty- 

 four hours. The acid is then wrung out in a steel centrifugal, and 

 the wrung gun cotton is thrown in small lots into an immersion 

 tank containing a large volume of flowing water, in which a paddle 

 wheel is revolving so as to rapidly dilute and wash away the residual 





Making Mehcuky Fulminate. 





acid in the gun cotton without permitting any considerable rise 

 of temperature from the reaction of the water with the acid. 



Even these severe means are not enough, for, as the cotton fiber 

 is in the form of hairlike tubes, traces of the acid sufficient to bring 

 about the subsequent decomposition of the gun cotton are retained 

 by capillarity. Therefore, after boiling with a dilute solution of 

 sodium carbonate, the gun cotton is pulped and washed in a beater 

 or rag engine until the fiber is reduced to the fineness of corn meal, 

 and a sample of it will pass the " heat test." This is a test of the 



resistance of gun cotton 



^=^ 



Detonator used in the United States Navy. 

 Contains thirty -five grains of fulminate of mercury. 



to decomposition, and re- 

 quires that when the air- 

 dried sample of gun cotton 

 is heated to 65.5° C in a 

 closed tube in which a moistened strip of potassium iodide and 

 starch paper is suspended, the paper should not become discolored 

 in less than fifteen minutes' exposure. 



This pulping of the gun cotton not only enables one to more 



