54 
MINUTES OF PROCEEDINGS OF 
It will not be necessary to describe the siftings of all powders. The 
above will sufficiently explain tbe system followed. 
IV. Density. —This is tbe most important quality of gunpowder, 
and must therefore be accurately determined, which can only be done 
by means of the mercury densimeter. The old gravimetric test—that 
is, “ cubing” or weighing a cubic foot of the powder—gives a fair 
indication of considerable variations in density, but may mislead, from 
differences in shape and size of grain. It is, moreover, perfectly useless 
to attempt to detect slight variations in density—variations which, 
though slight in degree, yet exercise immense effect on the qualities of 
the powder—by means of it. The cube-box is therefore no longer used 
at Waltham Abbey, being entirely replaced by the densimeter, with 
which the density of every pressing is ascertained before the manufac¬ 
ture of the powder is carried further. 
The Densimeter. 
The densimeter consists of a barometer-tube B, supported on a stout 
metal stand JD, and having a cock E at the bottom, by means of which 
it can be closed or opened. Attached to the top of it is a flexible tube 
1\ leading to the air-pump P, by means of which the air can be rapidly 
exhausted from the barometer-tube. A glass globe, fitted at each end 
with metal collars, on which again are screwed other collars provided 
with stop-cocks f and g, can be attached to the bottom of the barometer- 
tube, by means of a closely fitting screw. The lower collar of the globe 
is provided with a nozzle, which dips into an iron bowl C, filled with 
mercury. If then the lower cock g be kept closed, and the other ones 
opened, the air can be exhausted from the barometer-tube and globe; 
and the lower cock being then opened, the mercury will rush in and fill 
the globe, and continue to rise in the tube till it has attained the same 
