100 president's address — SECTION B. 



The following table gives the formula of — (1) Guncotton ; (2) 

 Nitro-glycerine ; and (3) Picric acid. For all practical purposes 

 these may be considered the bases of all smokeless powders. 



(1) Guncotton. — Trinitro-cellulose, Cg H^ O2 3 (NO3 ). obtained 



by the action of nitric acid upon cotton, thus : — 

 C6H7 0,3(HO) +. 3 HyQ3) = C.H^O a 3 (NQ3 ) + SH^^ 

 Cotton or Nitric Guncotton. Water, 



cellulose. acid. 



(2) Nitro-glycerine.— C3H5 3 (NO3 ), obtained by the action of 



nitric acid on glycerine. 



(3) Picric acid. — Trinitro-phenole, Q H3 3 (NO., ) O, formed by 



boiling carbolic acid or phenole and fuming nitric acid. 



As most of you are acquainted with the processes of the manu- 

 facture of guncotton and nitro-glycerine, it will be unnecessary to 

 describe them, but a few details referring to their properties may 

 be of interest. 



Guncotton possesses totally different properties from gunpowder. 

 Its temperature of ignition is from 250°-300° C. lower than that of 

 gunpowder, but at this comparatively low temperature it burns 

 away so rapidly that an experiment can be made on the palm of 

 the hand without any fear of scorching it. For the same reason a 

 piece of guncotton can be fired on a pile of gimpowder without 

 the powder being ignited. It is easily detonated by means cf a 

 falling weight, but the explosion is confined to the portion struck. 

 The pressure exerted by guncotton under the most favorable 

 conditions has been estimated by Berthelot to be 160 tons to the 

 square inch. The fact that all the products of the explosion of 

 guncotton are gaseous renders it smokeless. Only 50 per cent, 

 of the products of the ignition of gunpowder are gaseous. When 

 wet it is absolutely uninflammable, but even when containing from 

 1 5 per cent, to 20 per cent, of water it can be detonated by the 

 detonation of a dry primer of the same material. It presents many^ 

 special advantages for its application in naval and military opera- 

 tions; but as a smokeless powder it possesses one serious drawlsack, 

 viz., it does not produce a satisfactory proportion of permanent 

 gases during combustion, and, under certain circumstances, the 

 violent local action of the explosive makes it, jjer se, unsuitable 

 and highly dangerous as a propellant. 



Nitroglycerine enters into the composition of a very important 

 class of explosives possessing the generic title of " dynamite." 

 When pure it is a colorless mobile liquid, of sp. gr. 16 at 15-o° C. 

 When ignited in small quantities it burns slowly away, but when 

 heated to the temperature of 188° C. it explodes with great violence. 

 When spread in a thin layer it is extremely sensitive to slight con- 

 cussion or blow. At a temperature of 4° C. it takes the crystalline 

 form, and in this condition is far less sensitive to concussion or 



