BATCHES FOR ARTILLERY. 35 



ration by salts, we find, that the lighter the wood, the more 



saline matter it absorbs into its pores, or the interstices of 



its fibres. Hence it appears to me we may infer, that it 



contains less carbon than a heavier wood in a given bulk ; 



and that its combustion will evolve less caloric, since the 



caloric emitted is in the ratio of the quantity of oxigen 



combined with the combustible. It seems to me, that we This absofp- 



might class different kinds of wood, as to their combusti- their com b us ti» 



bility, by their absorption of salts ; and thus find which bility. 



would be most advantageous to burn for domestic purposes, 



whether we would have a rapid combustion, or a stronger 



and more continued heat. These researches will form the 



subject of a particular work, which I purpose on all our 



forest trees. 



The wooden matches, compared with port-fires, have the Comparison be 

 - „ . , tween the 



following advantages. wooden match 



The port-fire lasts but three or four minutes. and port-fires. 



A match a yard long will burn three hours. 



The port-fire is liable to break in the boxes. 



The match is strong, and easily carried about. 



The port-fire throws out dangerous sparks: 



The match confines its fire to itself. 



The port-fire costs from three pence to four pence half- 

 penny : 



The match costs but three half-pence or two-pence. 



The last consideration is of great importance, since, Great saving, 

 from calculations made in the war-office, what would cost 

 the state in the one case a thousand pounds, in the other 

 would not come to more than seventy-five*. 



As it was necessary to ascertain, whether these new The wood 

 matches would resist the rain, I had several burnt during Anguished 

 long and heavy rains, and they were not extinguished till by rain, 

 they were totally consumed ; their combustion being a little 

 retarded only. 



As the fabrication of these matches requires some care Precautions ne- 

 and precaution, I shall conclude this paper with a minute ? essa /y m ma *" 

 description of the process, agreeably to the request of 



* According to the estimates just before given, the saving would 

 ke much greater than i his on the lowest calculation. T. 



D2 ' his 



