46 CHEMISTRY. 



have already learned, it is necessary that the particles of 

 different substances should be in immediate contact, or ex- 

 ceedingly near to each other, in order that they may exert 

 their combining power. Now if any substance is heated 

 so hot that the atoms of which it is composed are separated 

 so widely that they pass beyond the range of their attrac- 

 tion, and new molecules form by a re-arrangement of the 

 atoms, the body is said to be decomposed by heat. 



42. Influence of the Nascent State. When the molecules of a 

 body are acted upon by any force which separates its constituent atoms, the 

 latter momentarily possess unusual attractive force, and are said to be in 

 the nascent state, or just born. The reason that a gas is so active in its 

 nascent state is supposed to be that at the very instant of its production 

 from some solid or liquid it is for that instant in a highly concentrated 

 state, not yet having expanded to the dimensions which it has in the gas- 

 eous state. Many gases which will not show any affinity for each other 

 under ordinary circumstances, if at the instant of their production, the mo- 

 ment of their birth, they are in immediate neighborhood of each other, 

 unite at once. The particles of the two gases thus produced are, in their 

 momentary concentrated state, so pressed in among each other that they 

 must unite if they have any affinity at all. When they are expanded there 

 is none of this pressure to bring the particles within the range of their at- 

 traction in other words, they are removed too far apart to exert a chem- 

 ical attraction upon each other. This being so, perhaps some one might 

 think that if a mixture be made of two gases, and great pressure in some 

 way be exerted upon it, these gases could be made to unite as they would do 

 in their nascent state. But the difficulty would be that no artificial press- 

 ure can bring them into so concentrated a state as they are in at the mo- 

 ment that they are produced in some fluid or solid. The state of conden- 

 sation in which gases are, as forming a part of solids or fluids, is far be- 

 yond any thing which mere pressure can produce. There are twenty-seven 

 gallons of oxygen in a single pound of iron rust. Is there any pressure 

 which man can produce in any way that can condense such a body of gas 

 into so small a space ? 



43. Catalysis Dissociation. There are other circumstances which 

 influence chemical attraction, among which should be mentioned what is 

 termed catalysis. This word is derived from two Greek words, viz., kata 

 "down," and luein, "to loosen," and is applied to the peculiar power ex- 



