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MINUTES OF PROCEEDINGS OF 
which, they furnish as to the somewhat unexpected readiness with which, 
under certain conditions, sparks, and even a stream of sparks, more oi 
less intense and continuous, may be obtained by friction from such 
metals as copper, gun-metal, and phosphor-bronze. 
This result can hardly fail to possess a practical interest for manufac¬ 
turers of gunpowder and other explosives, and for persons who are 
called upon to deal with and handle these substances. 
At the same time, these experiments, as might have been anticipated, 
bear ample confirmatory testimony to the very great superiority of 
copper, gun-metal, and phosphor-bronze to iron or steel in regard to 
the liability to “ strike fire.” 
Home Opeice, Whitehall, 
1st December, 1874. 
EXPERIMENTS. 
Series A.—A “ free grit ” stone, of the same description as is used for 
sharpening small tools and razors, 6 ins. diameter, revolving 1220 
revolutions per minute, and travelling 2079 ft. per minute, was 
supplied for these experiments, the material experimented with 
being in each case applied firmly to the revolving stone and held 
against it for about half a minute. 
Experiment No. I.—No. 2 phosphor-bronze. Occasional sparks and sometimes 
a stream.* 
Experiment No. 2.— No. 2 phosphor-bronze. Sparks amounting to a small, 
feeble, continuous stream. 
Experiment No. 3 -Gun-metal Jcnife (thin). Gave a few sparks, but no con¬ 
tinuous stream, and nothing like No. 2. 
Experiment No. 4. — Gun-metal lever (stouter section and altogether harder than 
the knife). Numerous sparks and at times slight stream, hut not quite so 
bad as 2. 
Experiment No. 5.— Gun-metal ingot , for making bolts, &c. (Good casting). A 
few sparks, but chiefly a continuous feeble stream (only the cast surface 
applied, see 10). 
* 1 did not witness this experiment; Colonel Younghusband, who did, furnished me with the 
result.—V. D. M. 
