MATTER AND FORCE. 67 



screen. A dozen square feet of surface are now covered 

 by those beautiful forms. With another solution we 

 obtain crystalline spears, feathered right and left by 

 other spears. From distant nuclei in the middle of the 

 field of view the spears shoot with magical rapidity in 

 all directions. The film of water on a window-pane on 

 a frosty morning exhibits effects quite as wonderful as 

 these. Latent in these formless solutions, latent in every 

 drop of water, lies this marvellous structural power, 

 which only requires the withdrawal of opposing forces 

 to bring it into action. 



The clear liquid now held up before you is a solution 

 of nitrate of silver a compound of silver and nitric acid. 

 When an electric current is sent through this liquid the 

 silver is severed from the acid, as the hydrogen was separ- 

 ated from the oxygen in a former experiment ; and I would 

 ask you to observe how the metal behaves when its mole- 

 cules are thus successively set free. The image of the cell, 

 and of the two wires which dip into the liquid of the cell, 

 are now clearly shown upon the screen. Let us close the 

 circuit, and send the current through the liquid. From 

 one of the wires a beautiful silver tree commences im- 

 mediately to sprout. Branches of the metal are thrown 

 out, and umbrageous foliage loads the branches. You 

 have here a growth, apparently as wonderful as that of 

 any vegetable, perfected in a minute before your eyes. 

 Substituting for the nitrate of silver acetate of lead, 

 which is a compound of lead and acetic acid, the electric 

 current severs the lead from the acid, and you see the 

 metal slowly branching into exquisite metallic ferns, the 

 fronds of which, as they become too heavy, break from 

 their roots and fall to the bottom of the cell. 



These experiments show that the common matter of 

 our earth c brute matter,' as Dr. Young, in his Night 

 Thoughts, is pleased to call it when its atoms and mole- 



