470 NITRE. 



cessively, although rapidly.* This powder has little effect on a ball 

 when fired in a gun. 



(A.) Another pulvis fulminans has been recently proposed, consist- 

 ing of nitre 2 parts, neutral carbonate of potassa 2, sulphur 1 and 

 marine salt 6, all finely powdered. It explodes with great energy. f 



(i.) Phosphorus. If a mixture of phosphorus and nitre be struck 

 forcibly with a hot hammer, a violent detonation takes place, and jets 

 of flaming phosphorus dart out laterally with danger to the spectators. 

 It is not a proper experiment before a class. 



(/.) Hydrogen gas. If a stream of this gas be passed, by a bent 

 tube, through melted nitre, the salt is decomposed with detonation, 

 and water formed ; the experiment requires caution. 



(k.) Powder of fusion 3 parts nitre, 1 sulphur, and 1 fine saw 

 dust, thoroughly mixed. If this mixture is surrounded by a rim of 

 sheet copper, and set on fire, the copper instantly melts, being con- 

 verted at the same time into a sulphuret. 



(/.) White flux equal parts of nitre and crude wine tartar, mixed 

 and deflagrated in a red hot crucible. 



(m.) Black flux 1 part nitre and 2 tartar, deflagrated in the same 

 manner ; it is a mixture of carbonate of potassa and charcoal. 



The substances, under ;, k, and Z, (especially the last,) are em- 

 ployed as fluxes, and for other purposes in small metallurgic operations. 



5. ACTION OF ACIDS. 



Decomposed by phosphoric and boracic acids, aided by heat. 

 Muriatic acid with heat, evolves nitrous acid and chlorine, a mix- 

 ture with which the alchemists, used to dissolve gold. (See chlorine.) 

 Sulphuric acid. The action of this acid has been mentioned. 



6. COMPOSITION. The equivalent of nitrate of potassa is 102 ; it 

 being an anhydrous salt, is composed of 1 proportion of dry nitric 

 acid 54-f 1 proportion of potassa 48 = 102. For 100 parts, of the 

 acid 52,94 -f alkali 47.06 = 100. 



In full detail, its constitution is, 



Oxygen 5 proportions, 5x8=40+ 1 prop, nitrogen, 14 = 54 



Potassium 1 proportion, 40 -}-l proportion oxygen, 8 =48 



102 



Thus we see how in a complex compound the numbers expressing 

 the combining powers of all the principles are united, according to 

 an admirable law. 



* Vide Black's Lectures, 1, 433, note 32. The difference is seen when a train is 

 fired on a board and another between two boards with weights upon them : the ra- 

 pidity of the combustion is greatly increased by the reaction of the flame, as in the 

 chamber of a gun. I Ferussac's Bulletin, Aout, 1828. 



