134 



Capt. Noble and Mr. F. A. Abel. 



[May 29, 



1 grm. of pebble 



powder evolved 712"6 units. 



R.L.Gr. 



F.Gr. 



C. & H. No. 6 



Mining 

 Spanish. 



717-0 

 7257 

 754-3 

 508-7 

 762-4 



"With the large explosion- vessel the results, Experiments 171 to 179 

 and 181 to 192, gave— 



1 grm. of pebble 



R.L.Gr. 

 F.Gr. 



C. & H. No. 6 



Mining 

 Spanish 



powder evolved 71 5'5 units. 



718-6 „ 



From the whole of these exper 



728-0 

 756-1 

 508-9 

 762-3 



iments, and giving to the second 



series, as probably the more accurate, twice the Aveight of the first 

 series, we arrive at the conclusion that the heat generated by the 

 combustion of the powders as actually used is as follows : — 



1 grm. of pebble 

 1 „ „ R.L.Gr 



F.Gr. 



C. & H. No. 6 



Mining 



Spanish 



powder generates 714*5 gramme-units. 

 718-1 

 727-2 



,, ,, 755*5 ,, 



508-8 

 762-3 



From an examination of the whole of the results it is obvious : 

 firstly, that the heat generated by the combustion of gunpowder is 

 subject to very wide variations, dependent upon the particular nature 

 of the powder employed (the Spanish powder for example generates 

 just 50 per cent, more heat than the mining powder) ; and, secondly, 

 that the heat evolved by the same description of powder varies in 

 different experLments to a greater extent than is to be accounted for 

 by errors of observation. And this was indeed to be expected, since 

 the very considerable variations in the products of combustion under 

 the same circumstances, as disclosed by the analyses, would hardly be 

 supposed to exist without some corresponding variation in the heat 

 evolved. 



The authors' views on this head are confirmed by calorimetric deter- 

 minations in their researches on gun-cotton. In these determinations, 

 which have been carried on with precisely the same apparatus, no 

 appreciable difference was found in the heat evolved in the various 

 experiments. 



The units of heat liberated, given above, are those furnished by the 



