4f>0 NITRIC AC It). 



(?i.) Boiled on sulphur, sulphuric acid is formed, but without 

 combustion. 



(o.) Poured on charcoal, there results a vivid inflammation; it is 

 best to pound ignited charcoal taken immediately from the fire ; put 

 it into a worthies glass vessel or a crucible, and add the acid gradu- 

 ally. Lamp black, or the charcoal of oils inflames more easily than 

 common charcoal, but a mixture of the two more easily than either 

 alone. 



(p.) Phosphorus is converted into phosphoric acid by the nitric ; 

 if weak, it merely boils with red fumes of nitrous acid $ if very strong, 

 and especially if warm, it burns with a splendid combustion; it is 

 thrown about in jets of fire and requires great caution ; to render it 

 the more beautiful, a tall narrow deep vessel should be used, but 

 when the quantity of both substances is considerable, there is some- 

 times a dangerous explosion.* 



(q.) If phosphoric acid is desired^ the common aquafortis is strong 

 enough ; it may be gently heated ; the phosphorus is added in pieces, 

 and when they are no longer dissolved, and readily take fire on com- 

 ing to the surface, the process is through. 



(r.) Heat will expel any remaining nitric acid, and if pushed far 

 enough in a platinum vessel, we obtain glacial phosphoric acid. 



(s.) The easily oxidable metals, iron, tin, zinc, copper, &ic. de- 

 compose the acid powerfully, especially if hot. 



(t.) Very strong nitric acid, poured from a glass fixed to a pole, fires 

 oil of turpentine, and other volatile oils the pole is for safety. A 

 little sulphuric acid is mixed with the nitric, to concentrate it by re- 

 moving a portion of water which it contains. The drying oils do not 

 need the addition of sulphuric acid. 



4. COMPOSITION AND COMBINING WEIGHT. When we have fin- 

 ished the history of the compounds of nitrogen and oxygen, we will 

 review that of nitric acid, which cannot perhaps be fully understood 

 without an acquaintance with all the acids and oxides, which have 

 nitrogen for their basis. We may state at present, that the propor- 

 tions of the elements of nitric acid, by weight, are, 



74.13 oxygen, - - 286 by volume, nearly 250 

 25.87 nitrogen, 100 " " ' 100 



100.00 386 



* This circumstance has happened so often in my own experience, with nitric acid 

 distilled from very pure nitre, with two thirds its weight of sulphuric acid, and with- 

 out any water in the receiver, that I cannot but repeat the caution that the operator 

 should be much on his guard. With a stick of phosphorus as long as a finger drop- 

 ped into 2 or 3 oz. of strong nitrous acid, 1 have known explosions like those of a 

 swivel, and the fragments of glass have wounded persons at a considerable distance. 

 See Am. Jour. for'Dr. Hare's experience. 



