520 
NATGRE 
[JuLy 16, 1914 
mercury is the most widely employed constituent of 
the detonator charge; sometimes it is used alone, 
but more usually with an admixture of 20 per cent. of 
potassium chlorate. 
Trinitrotoluene, picric acid, and tetranitromethyl- 
aniline, each with a small quantity of fulminate as 
primer, have also been used for charging detonators. 
More recently lead azide prepared from the sodium 
salt of hydrazoic acid N;H, by means of a lead salt, 
has also been used, as it has a greater power of 
initiating detonation, so that less azide is required to 
detonate an organic explosive than would be required 
of fulminate. Its manufacture, however, is more 
delicate than fulminate, and the formation of large 
crystals must be avoided, as they have the unpleasant 
property of sometimes exploding spontaneously. 
Another new explosive body which appears likely 
to play an important part as a charge for detonators is 
tetranitroaniline, manufactured by nitrating meta- 
nitroaniline, It combines an exceptional explosive 
power with aromatic stability and has a high density. 
It can be easily detonated, even when highly com. 
pressed, and has such a high percentage of oxygen 
that it can be detonated without residue or smoke. 
In blasting operations, gunpowder and detonators 
are either fired by a time fuse or electrically. The 
time fuse consists of a thin but continuous core of 
black powder covered by a case of twine and tape and 
varnish. It is made to burn at a known uniform rate, 
generally 2 ft. a minute, in order that a sufficient length 
can be used to allow the shot-firer, after lighting the 
fuse, to reach shelter before the explosion takes place, 
The instantaneous fuse, which burns at the rate of 
100-300 ft. a second. affords a mean of firing many 
charges simultaneously. 
Occasionally it happens that a coil is defective, 
generally through discontinuity in the powder core. 
C. Napier Hake, late Chief Inspector of Explosives 
for Victoria, ingeniously employed X-ray photography 
to examine suspected coils, and, in this way, was able 
to recognise those which were defective. 
One of the most interesting recent productions is the 
“detonating fuse,’”’ a soft metal tube filled with trinitro- 
toluene which detonates with greater velocity than 
most explosives. When placed alongside the cartridges 
in a deep borehole, it is considered to give an enhanced 
blasting effect by causing the whole charge to go 
off more simultaneously than when the column of 
explosive’ is fired at one end by a detonator in the 
usual way. 
With the object of preventing accidents so far as 
possible, and minimising the loss of life should an 
explosion occur, a number of rules and regulations 
have been drawn up by the Explosives Department 
of the Home Office which have to be followed in the 
construction and working of explosive factories. 
The object of the restrictions is to allow only limited 
quantities of explosive material and a limited number 
of workpeople in one building at a time, and, further, 
to place the different buildings at such distances from 
each other, or surround them by protecting earth 
mounds, that in the event of an explosion the effect 
is localised as much as possible and the explosives in 
the adjacent buildings are not “set-off.” 
The manufacture of guncotton and the other forms 
of nitrocellulose is carried out in the first stages in 
the non-danger part of the factory. . 
The most interesting development of the nitration 
process is the method devised by J. and W. Thomson, 
of the Royal Gunpowder Factory, Waltham Abbey. 
The composition of the acid mixture is of the 
greatest importance and largely determines the char- 
acter of the product. The ratio between the nitric 
and sulphuric acids and the water must be accurately 
adjusted, j 
NO! 2333, VOL. O39) 
' contents. 
It must also be remembered that the cotton is by 
no means a definite chemical body, and its physical 
state plays an important part. Samples of different 
cottons, under the same conditions in a bath of the 
same composition, while yielding nitrocelluloses con- 
taining practically the same percentage of nitrogen, 
may vary in solubility in ether-alcohol from 25 per 
cent. to 70 per cent. : 
Turning now to the production of nitroglycerine, 
this manufacture is much simpler than that of nitro- 
cellulose; at the same time, it is much more 
dangerous. 
The plant which is at present most employed is 
known as the nitrator-separator. It was developed at 
Waltham Abbey by Sir Frederic Nathan and W. 
Rintoul, and is a great advance on the former 
methods, 
The nitrator-separator is a cylindrical leaden vessel 
with a coned top; inside are placed leaden coils, 
through which cooling water circulates, and pipes, 
through which compressed air is blown to mix the 
The glycerine is introduced in the form of 
a fine spray under the acid by means of a special 
injector, worked also by compressed air. 
When everything goes right, the nitration of the 
bic. 4.—‘‘ Mounded ” house, Cotton Powder works. 
charge is usually completed in about one hour; the 
agitation with the air is discontinued and the separa- 
tion of the nitroglycerine from the acids takes place 
being lighter it comes to the top. <A pipe, in which 
a glass window is fitted, leads from the top of the 
nitrator-separator to a pre-washing tank; by allowing 
waste acid from a previous operation to enter at the 
bottom, the nitroglycerine is forced over into the 
washing tank; and the flow of acid is stopped when- 
ever all the nitroglycerine has passed into the washing 
tank, which can be observed through the window. _ 
With the object of preventing explosions of gas or 
coal-dust in mines, our Government, in common with 
many others, has instituted a test which explosives 
have to pass before they are put on the “ permitted”’ 
list, and are available for use in fiery or dusty mines. 
This test has varied in the different countries, and 
a change has been introduced recently, since the 
transference of the testing station from Woolwich to 
Rotherham. Much difference of opinion still exists 
as to the best means of carrying out such a test. 
One of the chief factors in determining the ignition 
is the temperature developed by the gases of explosion. 
Owing to lack of data, the temperature cannot be 
calculated with sufficient accuracy, and other condi- 
