416 DEFINITE NON-CARBURETTED EXPLOSIVE COMPOUNDS. 



Cr 2 3 (precip.) + H 2 (liquid) + O 3 + H 6 + N 2 = Cr 2 6 , 



(NH 4 ) 2 (solid) liberates + 44'5. 



Cr 2 3 (precip.) + 3 + 2H 3 N (dissolved) + H 2 (liquid) = 

 Cr 2 6 , (NH 4 ) 2 O = solid + 23'5 ; dissolved + 17'3. 



Some remarks are here necessary. 



The above figures are relative to a special state of chromium 

 oxide, namely when precipitated cold from dilute chrome alum, 

 by dilute potash, used in strictly equivalent quantity. But 

 they vary according to the manifold states of this oxide ; l the 

 variation by the precipitated oxide may amount to as much as 

 4- 6*9 Gal. according to the author's observations. With the 

 anhydrous oxide, and especially with the state produced by 

 ignition, 2 the difference would be even greater, a circumstance 

 which explains the greater resistance to the acids of calcined 

 chromium oxide. In the case of the formation of the chromates 

 the heat liberated must be diminished by the heat of transfor- 

 mation of the ordinary chromium oxide into calcined oxide, say 

 for example q. This quantity is, on the contrary, added to 

 the heat liberated by the explosive decompositions in which 

 the chromates intervene. 



4. Ammonium bichromate, briskly heated, becomes incan- 

 descent and is tumultuously decomposed with formation of water 

 and chromium oxide in virtue of a real internal combustion 



Cr 2 6 (NH 4 ) 2 = Cr 2 3 + 4H 2 0.+ N 2 . 

 This reaction liberates 



The water liquid, + 59 Cal. at constant pressure, +60*4 Cal. 



at constant volume. 



The water gaseous, 39'0 Cal. + q at constant pressure, + 

 40*4 Cal. at constant volume. 



The direct reaction of chromic acid on ammonia gas, in the 

 absence of water, would liberate nearly the double 



C 2 6 (solid) + 2NH 3 (gas) = Cr 2 3 + N 2 + 3H 2 (gas) + 

 73 '3 Cal. + 2 at constant pressure. 



5. The explosive decomposition of ammonium bichromate 

 produces the following gaseous volumes : 



The water liquid, 11 -2 litres (l + -^~) 



\ 2il6/ 



The water gaseous, 557 litres ( 1 -f- \ 



\ ZiioJ 



1 " Comptes rendus des stances de FAcad^mie des Sciences," torn. xcvi. p. 87. 

 1 Beraeims. 



