98 CHEMICAL DECOMPOSITION BY HEAT. 



Heat is diffused through all bodies in nature, and, as 

 we shall presently see, may be developed in many different 

 ways. We may, therefore, infer, that in converting a 

 sphere of ice into water, and that again into steam, we 

 have done nothing more than interpenetrate the mass 

 with a larger quantity of heat, by which its atoms are 

 more widely separated, and that thus its molecules 

 become free to move about each other. Hence, from a 

 solid state, the water becomes fluid ; and then, if the ex- 

 pansive force is continued, an invisible vapour. If these 

 limits are passed by the powers of any greatly increased 

 thermic action, the natural consequence, it must be 

 seen, will be the separation of the atoms from each 

 other, to such an extent that the molecule is destroyed, 

 and chemical decomposition takes place. 



By the agency of the electricity of the voltaic battery, 

 we are enabled to produce the most intense heat with 

 which we are acquainted, and by a peculiarly ingenious 

 arrangement Mr. Grove has succeeded in resolving 

 water by the mere action ot heat into its constituent 

 elements oxygen and hydrogen gases. That this decom- 

 position is not due to the voltaic current, but to the heat 

 produced by it, was subsequently proved by employing 

 platina heated by the oxy-hydrogen flame.* 



This interesting question has been examined with 

 great care by Dr. Robinson of Armagh, who has shown 

 that, as the temperature of water is increased, the affi- 

 nity of its elements is lessened, until at a certain point it 

 is eventually destroyed. This new and startling fact 

 appears scarcely consistent with our knowledge that a 



ceptions) proportional to the difference of temperature of the 

 metals." Transactions of the Koyal Society of Edinburgh, 

 vol. xii. 



* The Bakerian Lecture. On certain Phenomena of Voltaic 

 Ignition, and the Decomposition of Water into its Constituent Gases 

 by Heat : by W. K. Grove, Esq. Philosophical Transactions, 

 1847. Part 1. 



