32 MODERN SCIENCE READER 



greater and more accurate than anything he could have 

 employed, and the result with the old R. L. G. powder was 

 as follows: 



In a 6-inch gun with a shot weighing 30 pounds the 

 initial velocity was 2,126 foot-seconds, and the energy 

 realized was 972 foot-tons. With the weight of shot 

 trebled that is, increased to 90 pounds, the total velocity 

 fell to 1,370 foot-seconds and the energy increased to 1,178 

 foot-tons. 



Further increases in the weight of the shot to 120 

 pounds, 150 pounds, and 360 pounds gave energies prac- 

 tically identical, viz., 1,196, 1,192, and 1,192 foot-tons, 

 thus entirely confirming Robins' view. 



I think that I may venture to say that the question of 

 the pressures developed by fired gunpowder was set at rest 

 by the experiments made by myself and described in a 

 paper by Sir F. Abel and myself in the transactions of the 

 Royal Society. In these experiments I succeeded in 

 determining for the three powders of the English service, 

 pebble, rifle large grain, and fine grain, the tension of the 

 exploded gas at all densities up to unity, and in altogether 

 retaining the whole of the products of explosion, even of 

 charges of several pounds, which filled entirely or nearly 

 so the chambers of the explosion vessels. The results of 

 my experiments gave for a density of unity a pressure of 

 about 6,500 atmospheres. The temperatures of explosion 

 of the different gunpowders varied considerably, but were 

 generally between 2,000 C. and 2,230 C. 



I have never been able to understand why the consider- 

 able proportion of sulphur was so long retained as a com- 

 ponent of gunpowder. In the English service, shortly 

 before the adoption of modern propellants, it was almost 

 entirely dispensed with in cocoa powder, and with a view 

 of studying the question I had in 1883 four experimental 

 powders made; in two of these powders sulphur was dis- 

 pensed with, or nearly so; in the third, the amount of 

 sulphur was halved ; and in the fourth, the percentage was 



