THE ROYAL ARTILLERY INSTITUTION. 
57 
is filled with loose sand, and has an opening at the side, to admit of 
the 12 lb. projectiles being dug ont. The first wire screen or target is 
45 ft. from the gun, there being a screen of wood between them, with a 
hole for the passage of the shot. The second wire screen or target is 
120 ft. from the first, and therefore 165 ft. from the muzzle of the gun, 
and 15 ft. from the face of the butt. The gun used for proving powder 
of the R.L.G. class, is a 12-pr. M.L. wrought-iron gun, with Whitworth 
steel tube, rifled in three grooves; rifling (1 turn in 25 calibres) and 
vent special. It is used with 12-pr. shot (sometimes shot turned down 
9 lbs. have been employed), and a 1 lb. charge. 
The small-arms used are a Snider-Enfield and a Henry rifle; both 
fired with the service ammunition. 
The chronoscope used is one of Le Boulenge's, and has recently been 
so fully described in a separate pamphlet by Lieut. Charles Jones, It.A., 
Instructor in the Royal Cun Factories, that it is unnecessary to say 
more on the instrument here. The results obtained with it are ex¬ 
cellent. Three shots are fired from each sample of cannon powder 
subjected to proof, and from five to ten from each sample of small-arm 
powder. The observations of velocity agree very closely. Indeed, it 
may be predicted with tolerable safety, that if the powders fired have 
been made of the same materials (particularly of the same description 
of charcoal), under the same conditions, and are of equal density and 
of equal size of grain, they will give very nearly the same velocities* 
Any variation in density will tell at once. 
YI. Analysis. —This is generally conducted under the superin¬ 
tendence of the Chemist of the War Department, in the Royal Arsenal. 
Generally, a mixed sample from a number of stovings is submitted for 
analysis, as it is unnecessary to analyse the work of every day. It 
would be out of place here to enter into the details of the analysis, which 
will be found fully discussed in various chemical works. 
The quantity of moisture in the sample submitted is first of all ascer¬ 
tained, and the powder is then analysed. The process is a very simple 
one, and may be readily performed by any one—first, by dissolving 
out the saltpetre^ keeping up the process till the water which passes 
through the residue shows no trace of a deposit when evaporated, and 
taking special precaution against loss of charcoal in filtering; and 
secondly, by dissolving out the sulphur from the dried residue with 
bi-sulphide of carbon. The three ingredients can thus be separated 
and weighed. 
The proportion of ingredients which should be found in the gun¬ 
powder made at Waltham Abbey, is nearly-— 
Saltpetre. 75*248 
Charcoal. 14*850 
Sulphur. 9*900 
The excess of saltpetre is due to the fact that it has been for many 
years the practice to put in \ lb. extra to every 50 lb. charge which 
goes to the incorporating mill, to guard against loss in manufacture* 
8 
