APPENDIX. 305 '\ 



is soon liberated, and may be conveniently collected over { 

 warm water. The attraction of chlorine for the metals is in i 

 most instances extremely energetic : when copper leaf, or j 

 antimony, or arsenic in powder, are thrown into the gas, they ; 

 immediately enter into vivid combustion and form binary 

 compounds. Upon the French theory of combustion, oxy- ; 

 gen is absolutely necessary to the phenomena, but here are in- | 

 stances of brilliant inflammation without the presence of that \ 

 body (that is if chlorine be a simple substance, containing .; 

 no oxygen.) Other cases might be adduced, such as the ,! 

 combustion which ensues when copper filings and sulphur 1 

 are heated together in an exhausted vessel, or when potas- ; 

 sium and arsenic are made to combine under similar circum- i 

 stances. Comb'istion therefore is to be regarded as the ] 

 general result of the exertion of powerful chemical attraction, 1 

 and not as dependent upon any peculiar substance, or as r^  

 suiting from the decomposition of any distinct form of matter. 

 When phosphorus is introduced into chlorine, it sponta- \ 

 neously ignites and burns with a pale yellowish flame, pro- | 

 ducing a white volatile substance, composed of two proper- j 

 tions of chlorine and one of phosphorus. \ 



LESSON 67. i 



Electrical Mac1iine,jig. 49. A the glass cylinder. — B the i 

 prime conductor. — R the rubber, or cushion. — C the chain, j 



LESSON 68. ! 



Ley den Phial, Jig. 50. A a round brass ball at the ex- : 

 tremity of a wir'e, which passes through a cork D. R is a ^^ 

 discharging rod, — a a two brass knobs or balls attached to • 

 wires which are fastened to the handle at x. 



LESSON 70. 1 



Voltaic pile, Jig. 47. The pieces of copper, zinc, and : 

 woollen cloth, are supported with three rods of glass, as a 6, ; 

 ah, ah, and pieces of wood x and z. ^ 



\ 

 LESSON 7L I 



Fig. 46. A B a trough made of baked wood. — w w ar©^ \ 

 wires fastened to pieces of copper and put into the outer cells/ ^ 



