System of Chemistry, by Prof. Berzelius. 71 



ses, or to react with them without decomposition, is made by Berze- 

 lius an adequate reason for expunging the compound formed by one 

 atom of nitrogen with four atoms of oxygen from the list of the acids 

 of nitrogen. I do not, therefore, understand how the compounds re- 

 ferred to, while equally incapable of combination, can be considered 

 by him as acids. At first it struck me that the liquids consisting of 

 fluohydric acid, either with fluoboric acid, or with fluosilicic acid, 

 might be considered as merely united by their common attraction to 

 water, since they separate when this liquid is abstracted by evapora- 

 tion. Upon reflection, however, I retract that opinion, since it ap- 

 pears to me that if the compounds in question are to be considered 

 as acids, they may be viewed satisfactorily as fluacids with a double 

 radical ; but I deem it more consistent to suppose that a fluobase 

 of hydrogen in the one case unites with fluoboric acid, in the other, 

 with fluosilicic acid ; so that fluohydroboric acid, might be called 

 fluoborate of the fluobase of hydrogen, or more briefly, fluoborate of 

 hydrogen ; and in like manner, fluohydrosilicic acid would be call- 

 ed fluosilicate of the fluobase of hydrogen, or briefly fluoscilicate of 

 hydrogen. 



There are instances in which compounds, usually called bases act 

 as acids. Of course it is consistent that compounds, usually called 

 acids, should in some instances act as bases. In this respect, a stri- 

 king analogy may be observed between the union of the oxide of hy- 

 drogen (water) with the oxacids and oxybases ; and that of fluoride 

 of hydrogen with fluacids and fluobases. According to Berzelius, 

 water, in the first case, acts as a base, in the second as an acid. So 

 I conceive the fluoride of hydrogen acts as a base in the cases above 

 noticed, while it acts as an acid in the compound of hydrogen, fluor- 

 ine, and potassium, called by Berzelius ''fluorure potassique acide." 

 This compound I would call a fluohydrate of the fluobase of potassi- 

 um, or more briefly fluohydrate of potassium, as we say sulphate of 

 copper, instead of the sulphate of the oxide (or oxybase) of copper. 

 It appears from the inquiries of the author of the nomenclature under 

 consideration, that each of the three acids above mentioned as form- 

 ed by fluorine, with the three different radicals, hydrogen, boron, and 

 silicon, is capable, with electropositive metallic fluorides, of forming 

 the compounds treated of by him as double salts. These compounds, 

 to which I have already alluded, might be called fluohydrates, fluo- 

 borates, or fluosilicates of the metallic ingredient. As for instance, 

 the compoimd into which potassium enters, named by him "fluorure 



