7^ CHEMISTRY. 95 



13. What weight of N is there in 10 Ibs. <7/"HNO 3 ? 



N : HNO 3 : : x : to Ibs. 

 14 : 63 : : jr : 10 Ibs. 

 63 .* = 140 Ibs. 

 -r = 2g Ibs. (N). 



14. ./iftw much sal-ammoniac would be required to make 

 2 Ibs. <7/-H 3 N? 



H S N : H 4 N,C1 : : 2 Ibs. : or. 

 17 : 53.5 : : 2 Ibs. : x. 

 17 x = 107 Ibs. 



x = 6 T 5 f Ibs. (H 4 N,C1). 



15. Give illustrations of the replacement of the H in an 

 acid by a metal. 



(See Chemistry, page 44, note ; page 51, reaction ; and page 128, note.) 



1 6. What is the difference between liquid ammonia and 

 liquor ammonia ? 



Liquid ammonia is the gas condensed into a liquid by 

 cold: liquor ammonias is a solution of the gas in H 2 O. 



63. i. Why, in filling the hydrogen gun, do we use 5 

 parts of common air to 2 of H, and only one part of ' O to 



2 



Because the air is only \ oxygen, and hence 5 parts of 

 common air are equivalent to i part oxygen. 



2. Why are coal cinders often moistened with H 2 O before 



using ? (See Chemistry, page 57, note.) 



The H 2 O being decomposed by the heat of the fire 

 increases the combustion. 



3. What injury may be done by throwing a small quan- 

 tity 0/H z Oon afire ? 



" No more heat is produced by the action of the H 2 O, 



