\i si ST 1. 1915.] 



THE INDIA RUBBER WORLD 



591 



and this produces enough water in the course of a short while 

 to dilute the nitric acid. The thing desired is to have the acid 

 in its full strength attack the cellulose and thereby intensify the 

 ■ of the explosive so formed. A weakened nitration would 

 be a drau hack. Tlie clever chemist has overcome the difficulty 

 in this way sulphuric acid is mixed with the nitric acid because 

 sulphuric acid has a strong affinity for water. What follows? 

 Why. the sulphuric acid takes up the increasing moisture ami this 



Nitrated Cotton Being Dumped Into Steaming Vats. 



leaves the nitric acid unimpaired and capable of doing its full 

 work upon the cotton. 



The nitrating house at Indian Mead looks inside not unlike 

 a section of a big steam laundry, and, indeed, kindred facilities 

 are actually employed there. The cotton in being nitrated is put 

 in centrifugal wringers much like those in which clothes are 

 washed wholesale. When the nitration has reached the proper 

 point, and the artisan knows this, the cotton is roughly freed of 

 the bulk cf the acid by the mechanical wringer. The men at the 

 machines are apparently indifferent to the intensely acrid at- 

 mosphere which bites the unaccustomed throat and nasal pa! 

 -.i-i - Bui just the same, these workers have to he very careful, 

 and here is where rubber protects them. In addition to long 

 rubber gloves ami rubber boots they wear aprons of the same 

 sort which cover the front of the body, the hips and the legs 

 well down below the tops of the boots. 



When the cotton has soaked long enough in the acid it shows 

 signs of incipient combustion by giving oft a dense brownish 

 smoke. \t once the material is dumped into vats, where water 

 is turned upi n ;t by means of rubber hose. After being properly 

 "drowned" the cotton is taken out and partly freed of its liquid 

 content by mean- of other mechanical wringers. The stuff is 

 now guncotton or pyro-cellulose. What follows is something 

 in the nature of a paradox. Just as determined as the experts 

 were to thoroughly saturate the cotton with nitric acid up to this 

 stage, they are now bent upon removing every trace of the 

 transforming chemical. Indeed, the stability of the explosive 

 subsequently and its value as a propellent depend upon the 

 thoroughness with which the succeeding operations are carried 

 nit. 



The "pyro"— to adopt the abridged term used at the factory — 

 is carried from the nitrating house in open tubs placed upon 

 flat cars, and transported to great steaming vats. Into these 

 it is dumped, and for the better part of 48 hours it is boiled 

 continuously, for the purpose of extracting the biggest part of 

 the free acid -till clinging to the cotton filaments. After two 



day- of "iling, the "pyro" is removed from the vats and car- 

 ried to the pulping house. 



In the pulping house the "pyro" is pulped and poached just 

 as are the materials used in paper making; and after anywhere 

 from 20 to 30 hours of this pulping the time depending 

 the acid index of the liquid — it is finally freed of the last trace 

 of the transforming chemical. Strange as it may seen, the 



boiling and pulping pi - do not vitiate the work of the 



initial nitration. I lie chemical change worked in the cotton is 

 a permanent one, and the subsequent operations are intended I i 

 ,e only the unabsorbed acid. The pulping house is a 

 wet place, and lure, too, the workers wear rubber boots and 

 rubber aprons, and, occasionally, rubber gloves, 'if course 

 rubber hose is used extensively. 



Immediately alter coming out of the pulping vats or tanks, the 

 problem i- to eel rid oi as much of the water as possible. The 

 slimj material is carried upon a licit of blanketing to a "wet 

 machine," ami from 'In rollers of this apparatus it issues in 

 containing in the neighborhood of 40 per cent, of moisture. 

 This must be got rid of. and to that end the pulped "pyro" 

 journeys to what is known as the dehydrating house. There all 

 An a eery limited percentage of moisture is removed by means 

 of successive applications of pressure. Hut this does not suffice. 

 The last trace of dampness is driven out of the "pyro" by a 

 topping or bath of alcohol. 



X^.iin, the powder maker ha? borrowed from domestic life, for 

 the next machine is a mechanical kneader like those to be 

 found in large steam bakeries. Into this kneader the "p 

 witli its percentage oi alcohol, is dropped in the form of big 

 white discs. There the riyln proportion of ether is added, and 

 the mass is worked for 30 minutes. At the end of that time 

 (he product is not unlike damp cracker crumbs, and feels much 

 like them. The object of the kneading is to thoroughly mix in 

 the solvent of ether and alcohol. The material has undergone 

 another change by this process, and indeed is chemically smoke- 

 less powder. But there are yet a number of things to be done 

 before it is fit to be issued to the naval service and safe for 

 firing in the guns afloat. 



Various applications of pressure now follow, and this gives 



Copyright 1915, R. G. Skerrett. 



Presses UsEn fi k Driving Out Water and Forcing in Alcohol. 



the "colloid." for such it technically i~. its required homogeneity. 

 First, it is pressed into cylindrical cakes weighing about 50 

 pounds each, and to the inexpert the substance might be mis- 

 taken for crude rubber. It has a certain measure of elasticity 

 when dropped, and will rebound. Into the press again the 

 cakes go, coming out through sturdy steel colanders in the 



