THE EOYAL AETILLEEY INSTITUTION. 
87 
latter part of the process, viz. the purification from free acid, is differently 
managed, the cotton being left for three weeks in a stream, after which it is 
subjected to a further course of treatment with a solution of soluble glass. 
This is adopted partly with a view to retarding its rate of explosion, and 
partly to neutralize any lingering traces of acid which the washing may have 
failed to remove. It is also supposed to protect the gun-cotton by acting 
as a varnish upon the fibres, and making it less sensible to atmospheric 
influences. 
The solution may be driven into the cotton by means of a centrifugal 
machine, to which the liquid is supplied by a central tube; or it may be 
put into a large tub, and the cotton may be soaked in it. After this treat¬ 
ment the cotton is dried, then immersed in a stream far five or six hours, 
and once more washed by hand previous to being finally dried and put away 
for use. 
According to the patented process the gun-cotton is not treated with 
carbonate of potassa at all, but is boiled, after the first washing, in a weak 
solution of soluble glass, and is then immersed in a stream for about six 
days without any intermediate drying. Baron von Lenk attaches great im¬ 
portance to the treatment with soluble glass, but the examinations and 
analyses made by Mr Abel show that so very small a proportion of glass 
remains in the cotton after its final washing that it is impossible to 
understand how any protective effect, or any change in the rate of explosion 
can result therefrom. The point will probably be settled by experiments 
which will be made upon it. 
The skeins of cotton which, as already mentioned, are of different degrees 
of fineness, are now ready to be made up in such forms as are most 
convenient for practical use. Artillery cartridges are made by winding the 
cotton round hollow cones of wood of such length as will ensure the most 
effective results from the explosion, they are then put into flannel bags or 
any other envelopes for protection in packing and travelling, and are usually 
loaded in this state, the presence of the envelope being immaterial as 
regards the discharge. 
Bursting charges for shells are prepared by weaving the cotton into the 
form of a continuous hollow cylinder, or line, this being the most convenient 
way of inserting it through the fuze-hole. The same form is used for match 
lines, and also for small-arm cartridges. In making the latter however, 
webs of different sizes are required, so that one may be slipped on over 
another, and layers of paper interposed between them. This is adopted as 
the best arrangement for carrying out in fire-arms of this kind the object 
which is attained in pieces of artillery by the use of hollow cones. ( In 
Austria the most successful cartridges have been made with three layers of 
woven gun-cotton and two of paper. In all cases where a rammer has to be 
used, or a cartridge pressed into its place, the cotton must be so arranged 
that it will not undergo any compression, as results of considerable 
importance depend on the amount of space which it fills. 
Eor mining purposes, the most useful and effective way of applying the 
blasting charge is to make it up as a hollow twisted rope, and if shells for 
artillery fire have a cylindrical chamber which can be thrown open, it is 
desirable to fill them likewise with pieces of twisted rope exactly adapted 
to the interior space. 
