BORACIC ACID. 491 



4. It is thought that all the compounds of nitrogen and oxygen 

 are, essentially, gaseous bodies ; the two oxides are certainly so, and 

 can be combined with water in only small proportions. Other com- 

 binations have so strong an affinity for water that they have never 

 been entirely separated from it. Nitric acid is of this description, 

 and the two other acids unite very largely with water. 



5. In all the combinations of oxygen and nitrogen the elements 

 are in a state of condensation, excepting in the nitric oxide ; in this 

 gas, according to the opinion of Gay-Lussac, the oxygen and nitro- 

 gen have exactly the same density as in their free state ; but in the 

 other compounds the condensation is such that the oxygen gas does 

 not add to the volume ; or in other words the contraction is equal to 

 the volume of the oxygen gas. 



6. As among gases, the combining proportions correspond with the 

 volumes ; the least volume that enters into combination represents the 

 equivalent or smallest combining quantity. In the case of oxygen, 

 however, as already stated, the smallest combining proportion is con- 

 sidered as corresponding with half a volume, as in the composition of 

 water. 



7. It is obvious that, as the compounds of oxygen and nitrogen 

 differ from each other only in the proportion of oxygen which they 

 contain, they may be converted into each other by adding or abstract- 

 ing oxygen. This has been rendered apparent in the statements that 

 have been already given. Nitric acid, by its action on combustibles 

 and metals, is often converted into nitrous acid and nitric or even ni- 

 trous oxide ; and nitric oxide, by the addition of oxygen, forms the 

 nitrous acids and perhaps the nitric. 



SEC. VI. BORON AND BORACIC ACID. 



Remark. BORON being a substance unknown in common life, it 

 will be most convenient to describe first, the acid from which it is 

 obtained. 



BORACIC ACID. 



1. NAME AND DISCOVERY. The composition of this acid being 

 unknown when the nomenclature was formed, it was therefore named 

 from the Borax of commerce, its parent substance. 



The ancient name of sedative or narcotic salt was given to it by 

 Homberg, a chemist of the Academy of Sciences of Paris, who, in 

 1702, obtained it by distilling sulphate of iron and borax. 



2. NATURAL SOURCES. 



(a.) In the saline form, borax, from which chemists always obtain 

 boracic acid, is a native alkaline salt, having soda for its basis. It 



