THE EOYAL ARTILLERY INSTITUTION. 
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Experiment No. 6.— Gun-metal ingot, for making bolts, &c. (“Rotten” casting). 
A considerable uninterrupted stream of sparks, quite as bad as No. 2. 
Experiment No. 7.— No. 2 phospher-bronze again. See 1 and 2. Got at first 
a feeble stream, but not so bad as No. 6. 
Experiment No. 8.— No. 7 repeated. One or two faint sparks only. 
Experiment No. 9.— -No. 6 repeated. Got at once a continuous and lively 
stream of sparks. (The worst result up to this point). 
Experiment No. 10.— No. 5 repeated, but applying only the strictly metallic 
surface. A strong stream of sparks, occasionally interrupted, but generally 
continuous. About as bad as 9. 
Experiment No. 11.— No. 4 phosphor-bronze. Some very strong sparks, and 
at times almost a succession, but generally rather of the nature of a prolonged 
spark. 
Experiment No. 12.— No. 7 phosphor-bronze. One or two strong sparks, but 
no indication of a continuous stream, less than No. 11. (N.B.—This is the 
alloy usually employed for the tools and fittings of gunpowder works where 
phosphor-bronze is used). 
Experiment No. 13.— No. 8 phosphor-bronze (so hard that it can be used to 
chisel hard beech). Only one faint spark. 
Experiment No. 14.— Gun-metal ingot, same as employed in 10. A considerable 
succession of sparks, but not quite so bad as No. 10. 
Experiment No. 15.— Copper sheet (about -Jin. thick), for press plates, &c. An 
intermittent stream of small sparks. 
Experiment No. 16.— Gun-metal casting , for edge of press plate. 3 sparks. 
Experiment No. 17.— Iron rod (wrought-iron). A bright continuous stream of 
fire \ the sparks flew 6 ins. or. more in some cases. Very bright and intense. 
Experiment No. 18.— Hardened steel (file). Brilliant coruscations. 
Series B.— A cast-iron cylinder 6 ins. in diameter, and revolving at 
1220 revolutions a minute, was substituted for the “ free grit ” 
stone. 
Experiment No. 1.— No. 2 phosphor-bronze. No sparks. 
Experiment No. 2. — No. 7 phosphor-bronze. No sparks. 
Experiment No. 3.— No. 8 phosphor-bronze. No sparks, 
Experiment No. 4.— Gun-metal ingot. No sparks. 
Experiment No. 5.— Copper sheet, iin. thick. No sparks. 
Experiment No. 6.— Wrought-iron rod. A brilliant stream of fire. 
Experiment No. 7 .—Hardened steel. Brilliant and rapid flow of sparks, 
