318 Chronicles of Science. [April, 



interior blue cone is pointed, sharply defined, and extends only 

 about half-an-inch from the top of the tube. K polished platinum 

 surface is not acted upon by this flame, provided it be not brought 

 into contact with the interior cone. 



In the Bunsen burner, as usually made, the supply of air 

 depends upon the diameter of the tube, the holes at its base being 

 more than sufficient to supply the draught. With the wider tube, 

 it is necessary to limit the admission of air by depressing the tube 

 upon the lamp, when the force of the gas is diminished. Otherwise 

 the proportion becomes such that an exj^losive mixture is formed. 

 For this reason it is more convenient to use an arrangement in 

 which the excess of air can be regulated by an exterior tube sliding 

 obliquely dov/nward over the air-apertures. The gas-jet should 

 be on a level with the top of these apertures, which must be much 

 larger than those of the ordinary Bunsen' s burner. 



Mr. Brown, of the War Office Chemical Department, has 

 discovered a remarkable property connected with the ignition and 

 explosion of gun-cottcm. He has found that the explosive force of 

 gun-cotton may, like that of nitro-glycerine, be developed by the 

 exposure of the substance to the sudden concussion produced by a 

 detonation; and that if exploded by that agency, the suddenness 

 and consequent violence of its action greatly exceed that of its 

 explosion by means of a highly heated body or flame. It follows, 

 that gun-cotton, even when freely exposed to air, may be made to 

 explode with destructive violence, apparently not inferior to that 

 of nitro-glycerine, simj)ly by employing for its explosion a fuse to 

 which is attached a small detonating charge. Some remarkable 

 results have been already obtained with this new mode of exploding 

 gun-cotton. Large blocks of granite and other very hard rock, and 

 iron plates of some thickness, have been shattered by exploding 

 small charges of gun-cotton which simply rested upon their upper 

 surfaces. Further, long charges or trains of gun-cotton, simply 

 placed upon the ground against stockades of great strength, and 

 wholly unconfined, have been exploded by means of detonating 

 fuses placed in the centre or at one end of the train, and produced 

 uniformly destructive eflects throughout their entire length, the 

 results corresponding to those produced by eight or ten times the 

 amount of gunpowder when applied under the most favourable con- 

 ditions. Mining and quarrying operations, with gun-cotton api)lied 

 in the new manner, have famished results quite equal to those 

 obtained with nitro-glycerine, and have i)roved conclusively that if 

 gun-cotton is exploded by detonation, it is unnecessary to confine 

 the charge in the blast-hole by the process of hard-tamping, as the 

 explosion of the entire charge takes place too suddenly for its effects 

 to be appreciably diminished by the line of escape presented by the 

 blast-hole. Thus the most dangerous of all operations connected 



