M. J. R. Mayer on the Forces of Inorganic Nature, 373 



We will in the first instance take matter, to afford us an 

 example of causes and effects. Explosive gas, H + 0, and water, 

 HO, are related to each other as cause and effect, therefore 

 H-f = H0. But if H-fO becomes HO, heat, cal., makes its 

 appearance as well as water; this heat must likewise have a 

 cause, x, and we have therefore H + + x = HO + cal. It might, 

 however, be asked whether H + is really =H0, and a?= cal, 

 and not perhaps H-f = cal., and # = H0, whence the above 

 equation could equally be deduced ; and so in many other cases. 

 The phlogistic chemists recognized the equation between cal. 

 and x } or Phlogiston as they called it, and in so doing made a 

 great step in advance ; but they involved themselves again in a 

 system of mistakes by^ putting —x in place of ; thus, for 

 instance, they obtained H = HO + #. 



Chemistry, whose problem it is to set forth in equations the 

 causal connexion existing between the different kinds of matter, 

 teaches us that matter, as a cause, has matter for its effect ; but 

 we are equally justified in saying that to force as cause, corre- 

 sponds force as effect. Since c — e, and e = c, it is unnatural to 

 call one term of an equation a force, and the other an effect of 

 force or phenomenon, and to attach different notions to the ex- 

 pressions Force and Phenomenon. In brief, then, if the cause 

 is matter, the effect is matter ; if the cause is a force, the effect 

 is also a force. 



A cause which brings about the raising of a weight is a force ; 

 its effect (the raised weight) is, accordingly, equally a force-, or, 

 expressing this relation in a more general form, separation in 

 space of ponderable objects is a force; since this force causes the 

 fall of bodies, we call it falling force. Falling force and fall, or, 

 more generally still, falling force and motion, are forces which 

 are related to each other as cause and effect — forces which are 

 convertible one into the other — two different forms of one and 

 the same object. For example, a weight resting on the ground 

 is not a force : it is neither the cause of motion, nor of the lift- 

 ing of another weight; it becomes so, however, in proportion as 

 it is raised above the ground : the cause — the distance between a 

 weight and the earth — and the effect — the quantity of motion pro- 

 duced — bear to each other, as we learn from mechanics, a constant 

 relation. 



Gravity being regarded as the cause of the falling of bodies, a 

 gravitating force is spoken of, and so the notions of property and 

 of force are confounded with each other : precisely that which is 

 the essential attribute of every force — the union of indestructibility 

 with convertibility — is wanting in every property : between a 

 property and a force, between gravity and motion, it is therefore 

 impossible to establish the equation required for a rightly con- 



