282 
MODERN GUNPOWDER AND CORDITE. 
up to the charge house through the pipe which connects the bottom of 
the acid charge in the “egg,” with the tank A, in the charge house. 
The acids are then run by gravitation into the nitrating apparatus, a 
large cylindrical lead vessel, D, fitted internally with coils of lead pipes, 
through which a circulation of cold water can be kept up without 
letting any water mingle with the charge, and then the 330 lb. charge 
of glycerine is passed into a little tank, C, above the nitrating apparatus. 
The nitrating operation takes place as soon as the acids are in, and 
they are kept in a state of effervescence by air, which is pumped 
through perforated tubes at the bottom of the apparatus. The gly¬ 
cerine is allowed to pass through an injector, which can absolutely 
control the rate of supply of the glycerine to the acids. The tempera¬ 
ture is most carefully observed and regulated during this process, and 
as any abnormal rise immediately indicates danger, an elaborate system 
of control is maintained. The maximum temperature permissible is 70° 
Fahr. 
The uniformity of temperature throughout the charge, and also 
intimate mixture of the glycerine with the acids, is ensured by a con¬ 
stant inflow of air through perforated lead pipes in the apparatus. The 
air so injected keeps the charge in a constant state of effervescence. 
The temperature of the charge is regulated, in the first instance, by 
the rate at which the glycerine is allowed to flow into the acids. 
2nd.—By the cooling influence of the water passed through the lead 
coils. 
3rd.—By injecting carbonic acid, which is kept, for emergencies, 
under pressure, in an iron cylinder close to the apparatus. 
If the temperature still rises and gets out of control, the whole charge 
is immediately run off into the drowning tank (D.T. in Plate II), which 
contains about 10,000 gallons of cold water. 
If the nitration proves satisfactory the operation is completed in 
about an hour, and the 330 lbs. of glycerine are converted into 660 lbs. 
of nitro-glycerine, mixed up in a sort of foaming liquid with the acid 
in the nitrating apparatus. It is then passed away to the separating 
tank where it is allowed to stand for about an hour. There is a little 
glass window in the separating tank, through which the layer of nitro¬ 
glycerine, a few inches thick, can be seen floating on the top of the 
acids like an oily liquid. When the separation is completed the acids 
are allowed to run off to the waste house or “ After-nitrating house ” as 
it is called, from the nitrating bouse, and the nitro-glycerine is run into 
the first washing apparatus and washed with a solution of soda in water, 
in a large tank which is also kept in a state of effervescence by injected 
air. Then from the first washing it goes on to the second washing in 
another house, passed on by pipes, and is there washed with hot water 
and soda for about four hours. The nitro-glycerine is now at the 
bottom of the tank. Water floats on nitro-glycerine and nitro-glycerine 
floats on acid, and the houses, tanks, &c., are so arranged as to levels, 
that gravitation can be used as much as possible, in all shifting or 
transfer operations, to avoid pumping, striking, or using violence with 
nitro-glycerine. Then the nitro-glycerine is filtered off through a bag 
of table salt, sodium chloride, and is passed on to the store tanks, 
