CHEMICAL SCIENCE. 235 



use of the most approved instruments. On his passage from Europe 

 to South America, M. Levy made experiments to ascertain the pro- 

 portions of oxygen and of carbonic acid contained in the air upon the 

 surface of the ocean by night and by day. He invariably found that 

 these ingredients were in greater proportion during the day than dur- 

 ing the night, and in fine weather than during cloudy weather. 

 Paris Correspondent of the National Intelligencer. 



GUN-COTTON, AND NEW EXPLOSIVE COMPOUND. 



GUN-COTTON dissolved in ether has, it is well known, been suc- 

 cessfully employed as an application for incised wounds. When 

 washed over the surface, the ether, rapidly evaporating, leaves behind 

 a film which is impervious to air ; and thus the wound, protected 

 from atmospheric influences, heals by the first intention. This curi- 

 ous compound has been also employed successfully as a remedy for 

 toothache. The cavity of the tooth being cleaned out, a little asbes- 

 tos saturated with collodion, as it is called, in which a little morphia 

 is added, is placed in it. All soon becomes solid ; and thus an excel- 

 lent stopping and a powerful anodyne are applied at the same time. 



Gun-cotton was used, for the first time in actual warfare, at the 

 siege of Moultan, India. The brilliance and breadth of the flash of 

 the guns fired by this new adaptation of science to the devastation of 

 war are described as of terrific intensity. 



A series of experiments relative to the temperature at which gun- 

 cotton explodes have been instituted by Dr. C. Marx. It results from 

 these, that it explodes even at 144 F., but on an average at 199, 

 when raised to this temperature from that of the air within five min- 

 utes. Further, that it does not explode when heated so slowly that 

 the temperature is not increased more than 5 F. per minute, but be- 

 gins to be slowly decomposed at 131, and its explosive force is very 

 much weakened with the progress of the decomposition. This cir- 

 cumstance deserves attention in respect to the conveyance of explosive 

 cotton, as metallic objects readily acquire a temperature of 144 by 

 exposure to the sun. Poggendorff's Annalen, LXXV1II. 



New Explosive Compound. The following is the recipe for a new 

 explosive compound, discovered during the past year, said to have ten 

 times the force of gunpowder. One part yellow prussiate of potash, 

 well dried ; one part sugar, well dried ; two parts chlorate of potash. 

 These materials are finely ground separately, and then intimately 

 mixed. This compound differs from ordinary gunpowder in being 

 explosive even in the form of fine powder, no granulation being neces- 

 sary. Other advantages claimed for it are its easy formation, the in- 

 gredients previously powdered may be mixed only when wanted ; the 

 absence of action of air on the separate materials, while charcoal for 

 gunpowder is injured by exposure ; and, lastly, the greater force. 

 On the other hand are its corrosive effects on iron barrels, for which 

 bronze must be substituted, and its dangerous inflammability. It is ex- 

 tremely dangerous to introduce gunpowder, sulphur, or charcoal into 

 the mixture, the smallest quantity causing a violent explosion when 

 ignited. 



