450 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



is called the Chemical Armor for Bank Vaults, which is so 

 adjusted that, should the interior of the safe be penetrated 

 by violence, sundry glass vials filled with sulphuric acid are 

 necessarily broken, and their contents discharged into pow- 

 dered carbonate of lime, resulting in the instantaneous pro- 

 duction of enough carbonic-acid gas to asphyxiate a regi- 

 ment. What mode of defense will be adopted by the oppo- 

 site side, should this device be carried out to any extent, re- 

 mains to be seen. 



NEW METHOD OF SLAUGHTERING ANIMALS. 



Killing animals by the so-called boutrole, first used in Paris, 

 and recently introduced into Vienna, seems preferable to the 

 old method, since an animal can be instantly killed by a single 

 blow with an instrument weighing scarcely five pounds, in- 

 stead of the ten to fifteen blows with the heavy hammer usu- 

 ally employed. The instrument is simply a very convenient 

 form of axe, with a hollow cylinder (like a gun-wad punch) 

 about six inches long and one inch in diameter, with its edge 

 ground sharp, on the end opposite the blade. A single blow 

 with this end cuts a round hole in the forehead, and produces 

 instant death. 9 (7, November, 1873, 163. 



CLEANSING SPONGES. 



According to J. Stinde, sponges that have become soiled, 

 hard, and discolored by photographic use, may be again ren- 

 dered perfectly pure and elastic by immersion in a wine-col- 

 ored solution of permanganate of potash, and then in dilute 

 hydrochloric acid (one part of acid to ten of water), and aft- 

 erward washed thoroughly with water. Sufficient time should 

 be given to the different parts of the operation. 5 (7, 1873, 

 xlii., 336. 



plastic carbon foe filters. 



According to Professor Kletzinsky, two mixtures have 

 been found best adapted to this purpose in practice : the 

 one consisting of 60 parts of coke, 20 of animal carbon, 10 of 

 charcoal, and 10 of pipe-clay; the other of 10 parts of coke, 

 30 of animal carbon, 20 of charcoal, and 40 of short-fibred 

 asbestos. The ingredients, except the asbestos, are finely 

 powdered, passed through a sieve, and intimately mixed while 



