Chemistry and Physics. 219 



the same or of another base. To this class belong the chlorides, 

 nitrates, and normal sulphates of the fixed alkalies. In the second 

 class of acids and bases, Berthelot places those which are decom- 

 posed by water progressively, the decomposition increasing with 



either indefinitely, or possessing a definite limit. To this class 

 belong borates, carbonates, cyanides, sulphides, alkali phenates, 

 acetates, butyrates and valerianates. Sometimes the decomposi- 

 tion takes placed in its entirety by the first portion of water 

 added; so that the thermometer shows an absoi-ption of heat 

 nearly equal to that which is evolved in the original formation of 

 the salt. Such are the salts formed by the alkalies with alcohol, 

 glycerin, mannite, etc. Of course the decomposition by water is 

 the more marked when the base is also feeble, like the oxides of 

 the heavy metals. In this case, the decomposition is apparent 

 even with acids of the first class. Even 

 strong acids are thus decomposed, though 

 when the acid is weak. The author draws the c 

 solution, strong acids always unite with strong bases, leaving the 

 feebler membere to each other. To account for the stability of 

 the alkali-salts of strong acids, he supposes that the formation of 

 definite hydrates by the union of water with the acid and the base, 

 taken separatelv, under the conditions of the experiment, sets free 

 a total amount of heat which is less than that evolved in the for- 

 mation of the normal salt itself. So, reciprocally, if the alkali-salts 

 of feeble acids are decomposed by water, the reason is to be found 

 in the excess of the thermic efiects due to the formation of 

 hydrates over those which result from the formation of the normal 

 salt. Several of the many important considerations which flow 

 from this hypothesis are given at length in the paper.— C E., 

 Ixxxi, 844, Nov., 1875. G. F. b. 



9. Division of an Acid among several Bases.— M. Biorthklot 

 has endeavored to solve the question whether, if an acid is present 

 with several bases, it will unite with one, or be divided among 

 them. Berthollet believed that each base would take an amount 

 of thef •" - - 



ty; f( ^ 



Tersely as its equivalent: or, if the , . 



amounts proportional to their atomic weights, each would take 

 half the acid. Gay Lussac believed that a complete mixture took 

 place, and that the salts were formed only when separated by 

 their insolubility, crystallization or volatility. To test these 

 views, two bases were selected which disengaged an unequal 

 amount of heat in uniting with the same acid. Thus mixtures of 

 equivalent weights of chloride of ammonium and caustic soda 

 were mixed. The difference in this case of the two bases would 

 equal 1-12 units of heat. Were the theory of Berthollet correct, 

 half of the acid should go to the soda 'setting free -56 units of 

 lieat. Other divisions of the acid might set free any quantity 

 from to M2. According to Gay Lussac there should be no 



