CHEMICAL SCIENCE. 211 



dcr will be required for 100 parts of the common kind. The residue 

 of the white being as 31.53 to 68 of the black, it is more cleanly, 

 while the heat generated when it is ignited is much lower, and a 

 greater number of shots can be fired with it without heating a can- 



c? O 



non. 



M. Pohl considers that white gunpowder, being more energetic in 

 its action than common black powder, approaches more nearly gun- 

 cotton for efficiency, and it has the advantage over this substance in 

 being more easily prepared, keeping for a longer period of time with- 

 out change, and is cheaper. This powder is not only easier of prepa- 

 ration than the old, but it may be made in a few hours in great quanti- 

 ties with very simple machinery. M. Pohl states that it is difficult of 

 explosion by pressure and percussion ; but Mr. F. Hudson, in a com- 

 munication to the London Chemical News, states that he made sev- 

 eral samples according to M. Pohl's receipts, and found that when he 

 mixed the materials moist, then dried them at 150 Fah., the powder 

 was very liable to explode with friction it was indeed percussion 

 powder. This was not the case when they were mixed dry. He 

 says : "A cannon loaded with white gunpowder goes off on the ap- 

 plication of a few drops of sulphuric acid applied at the touch-hole. 

 The property of this gunpowder may possibly be applied to some ad- 

 vantage in the preparation of bomb-shells for long ranges. These 

 shells would not explode until they strike the object, if filled with 

 white powder, and contain a small glass vessel with sulphuric acid. 

 No explosion of the shell would take place in the air, as is too often 

 the case with the ordinary fuse shell." 



AESEXIATED ALCOHOL. 



Arseniated alcohol has been employed by M. Leprieur for the 

 preservation of specimens in natural history collections, especially 

 insects. The animal tissues to be preserved should be plunged into 

 the liquor shortly after death, and insects while still living, or after 

 suffocation by chloroform or ether vapor. M. Leprieur, who has suc- 

 cessfully employed this method for twelve years, adds that the living 

 insect is increased in weight about a fourth after remaining in the 

 liquid twelve hours, and that they retain in their organs quite enough 

 arsenious acid to repel the attacks of larvae. 



A METHOD OF SEPARATING ISTICOTINE FKOM THE SMOKE OF 



TOBACCO. 



In order to separate nicotine from tobacco-smoke, M. Ferrier pro- 

 poses to furnish pipes and cigar-holders with a tube containing a pe- 

 culiarly-prepared cotton. He hopes by this arrangement to obviate 

 the inconveniences and dangers incident to the occasional or habitual 

 practice of tobacco-smoking. To prepare the cotton, it is soaked in 

 a solution of tannin, and then dried in the air. When the smoker 

 draws the air through the bowl of his pipe, or the leaves of his cigar, 

 a current of gas and vapor is formed, consisting of air with excess of 

 nitrogen, of carbonic acid, and vapor of water, products of the com- 

 bustion of the outer layer of the tobacco, and of the empyreumatic 

 matter produced from the portions of tobacco adjoining the burning 



