100'.)] on Guncotton and Nitroglycerine. 4o3 



earthenware pans. These pans are grouped together and worked in 

 sets of four. The bottom of the pan slopes downwards to a central 

 hole, connected by suitable pipes and cocks to a pipe supplying the 

 nitrating acid, and to other pipes through which tlie waste acid is 

 removed on completion of nitration. The pans are covered with 

 aluminium hoods connected to an exhaust-fan, for carrying off 

 fumes. 



Nitrating acid is then run in up to a definite mark, and a charge 

 of 20 lb. of dry cotton waste is immersed in the acid in each pan in 

 small quantities at a time. A.\\ ahiminium fork is used for the pur- 

 pose. When the charge of cotton waste has been dipped, perforated 

 earthenware plates are placed on the top of it, to keep it all under 

 the surface of the acid ; a film of cold water is run on to the sur- 

 face of the plates and serves as a seal to prevent fumes getting into 

 tlie room, and the aluminium hoods are removed. The cotton 

 w^aste remains soaking in the acid for two and a half hours : at the 

 expiration of that time its conversion to guncotton is complete. 

 The cock leading to the waste acid pipe is then opened and the waste 

 acid allowed to flow away from the guncotton at a definite rate, 

 whilst cold water is allowed to flow on to the top of the perforated 

 plates at an equal rate. The water follows up the acid through the 

 guncotton without any appreciable mixing of the w^ater and the acid 

 taking place, and Avhen the whole of the acid has been displaced in 

 this w^ay, the water is allowed to drain away from the gun-cotton, 

 which is then ready for the final purification jjrocess. This system 

 of manufacture possesses many advantages over the systems which it 

 is superseding. Foremost among them are : — 



1. Decreased cost of manufacture, due to the facts that for a 

 given output very much less labour is required ; that the plant is 

 both very cheap and very durable ; that no power is required to work 

 it : thatless acid is lost in the w^ashing processes ; and that, owing to 

 the absence of fumes and spilt acid, the cost of maintenance of the 

 buildings is reduced. 



'1. Increased safety as far as personnel is concerned, because there 

 is no escape or splashing about of acid, which in the old processes 

 was a fruitful source of acid burns, and also because decompositions, 

 w^hich used to take place both in the digesting pots and in the acid 

 centrifugals, with the consequent evolution of poisonous oxides of 

 nitrogen, no longer occur. 



:-). A better guncotton is obtained. It is freer from unconverted 

 cotton, and as the whole of the nitration and preliminary washing 

 operations are carried out in earthenware receptacles, it is freer from 

 mineral impurities. 



4. An increased yield to the extent of about 7 per cent, is realised. 



The manufacture of guncotton was not commenced at the Royal 

 Gunpowder Factory, Waltham Abbey, until the year 1872. Shortly 

 after that date an improvement was made in the purification pro- 



