86 FRAGMENTS OF SCIENCE. 



of the metal are thrown out, and umbrageous foliage loads 

 the branches. You have here a growth apparently as won- 

 derful 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 there you 

 see the metal slowly branching into these 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 — " brute matter," as Dr. Young pleases to call it — 

 when its atoms and molecules are permitted to bring their 

 forces into free play, arranges itself, under the operation of 

 these forces, into forms which rival in beauty those of the 

 vegetable world. And what is the vegetable world itself 

 but the result of the complex play of these molecular forces ? 

 Here, as elsewhere throughout Nature, if matter moves, it 

 is force that moves it ; and if a certain structure, vegetable 

 or mineral, is produced, it is through the operation of the 

 forces exerted between the atoms and molecules. These 

 atoms and molecules resemble little magnets with mutually 

 attractive and mutually repellant poles. The attracting 

 poles unite, the repellant poles retreat, and vegetable as 

 well as mineral forms are the final expression of this com- 

 plicated molecular action. 



In the formation of our lead and silver trees, we needed 

 an agent to wrest the lead and the silver from the acids 

 with which they were combined. A similar agent is re- 

 quired in the vegetable world. The solid matter of which 

 our lead and silver trees were formed was, in the first in- 

 stance, disguised in a transparent liquid ; the solid matter 

 of which our woods and forests are composed is also, for 

 the most part, disguised in a transparent gas, which is 

 mixed in small quantities with the air of our atmosphere. 

 This gas is formed by the union of carbon and oxygen, and 



