222 



CHEMISTRY. 



CHAPTER XVII. 



GROUP II. BAKIUM, STRONTIUM, AND CALCIUM. 



308. Barium and Strontium. These metals do not occur 

 native, their properties being in this respect much like 

 those of Group I. Barium salts are widely distributed, 

 but not in very great quantity. Strontium compounds 

 are comparatively rare. Both occur as sulphates and car- 

 bonates. Barium sulphate or larytes is used to adulter- 

 ate white-lead paint. Barium salts are poisonous. Bari- 

 um nitrate is used in making the green fire of fireworks, 

 and strontium nitrate for the red fire. AVe will give you a 

 receipt for a red fire if you will be 

 careful in making it : Take 80 parts 

 of dry strontium nitrate, 22 of sul- 

 phur, and 5 of lampblack ; mix these 

 intimately in fine powder ; then add 

 20 parts of potassium chlorate cau- 

 tiously and without rubbing. Mix 

 well on paper. This burns with a 

 brilliant crimson flame. Make no 

 more than you want to burn, for 

 it is dangerous to keep it. 



309. Fire Under Water. If this 

 mixture be put into a paper case, A, 

 well stopped with varnish at the end, 

 and then, after being set on fire, be 

 introduced into a jar of water, CC, it 

 Fig. so. w ill continue to burn under water, 



