180 M. Berzelius on certain points 



each combination, this idea of Mr. De Bondsdorff would 

 without doubt be preferable; but if attention be due to the 

 chemical properties which characterize combinations, we can* 

 not adhere to an arrangement founded on the number of the 

 elements. Yet so essential is it in chemistry to have reference 

 to properties, that a system of chemistry in which common 

 and analogous properties should not affect the arrangement, 

 would present a mass of facts so chaotic, that no memory 

 would be competent to retain them. In a system thus strictly 

 conformable to the ideas of Mr. De Bondsdorff, cyanogen, 

 though in its properties resembling chlorine or bromine which 

 are simple bodies, ought to be considered, also, as a base or 

 as an acid having azote for its radical — I am persuaded you 

 would not approve of extending the system of De Bondsdorff 

 so far; but if it be correct, it would be inconsistent not to 

 make this extension. 



But let us return to the combinations of the metals with 

 chlorine, fluorine, &c, and make, in imagination, the following 

 experiment. Let us take two portions of caustic potash, a 

 base in which the basic characters are more striking than in 

 any other. To one, let us add a sufficiency of sulphuric acid 

 to extinguish entirely its basic property; we shall then have 

 a neutral body of a saline taste. You will admit it to be a 

 salt. Now let us add to the other portion, hydrofluoric acid. 

 At a certain point the basic properties of the potash will dis- 

 appear, and we shall have a resulting compound quite as 

 neutral as the sulphate of potash, endowed with a saline taste 

 entirely analogous to that of the sulphate. The basic pro- 

 perties of the potash are destroyed by the hydrofluoric acid, 

 as well as by the sulphuric acid. But you will allege the re- 

 sulting combination is not a salt, but a base which has ex- 

 changed one basifier (oxygen) for another basifier (fluorine). 

 In proof you may add as much more hydrofluoric acid, which 

 combining with the new base will form with it a crystallized 

 salt. But this salt is not neutral, it has almost the same acidity 

 of taste as the hydrofluoric acid employed. The new base 

 does not destroy then the acid reaction. 



Let us make a further addition of sulphuric acid to the sul- 

 phate of potash. A salt equally acid will result, in which the 

 sulphate of potash acts the same basic part towards the sul- 

 phuric acid, as the fluoride of potassium towards the hydro- 

 fluoric acid. Should it be desired to extend the comparison 

 further, it will be found that for each less electro-positive 

 fluoride, susceptible of combination with the potassic fluoride, 

 there will be, with but very few exceptions, a corresponding 



