214 <^N THE COMBINATIONS OF OXIGEN. 



takes place, the subject will not want importance and inte- 

 rest to those who are about to begin the elevated study of 

 chemistry : to such it will at least afford a useful aid to the 

 memory, much to be desired. 



The first two of these propositions will be perceived to be 

 very generally known : it is the third, which is the most ex- 

 traordinary, and which renders the former of more import- 

 ance. 

 Laws of the First then it is known, that substances containing oxigen 



combinations ^^m -^ ^ j^ j^^^ ,^^^^ 2dly, substances which do not 



ot oxigen. -^ ' 



contain this principle readily and mutualli/ combine : but, 



3dly, I believe no substance containing oxigen will combine 

 with a substance, which does not contain oxigen. 

 Acids combine I shall now endeavour to elucidate and support the pre- 

 ^ut not with ceding propositions; and no circumstance can do this more 

 metals. , forcibly, than the universal chemical fact, that metals do 



not dissolve in acids, until they have, by some means, ac- 

 quired oxigen ; but the instant the oxidation is accomplish- 

 Alkalis do the ed, the solution Jiakes place. In the same manner the 

 same. alkahs do not combine with the metals, but the metallic 



oxides and the alkalis do combine, e. g. the ammoniuret of 

 Metalssepa- copper, &c. ; again, the metals during the process of oxida- 

 ides aT'^ "'^" ^^°" immediately separate from the oxide when formed. 

 formed. But to reduce the subject into its simplest form, we may 



observe — 

 Classification 1. That the metals, metalloids, and simple combustible 

 ofbodiesthat bodies, combine with each other. 2. The oxides of the 

 metals, the alkalis, and the acids, formed of the combusti- 

 ble bodies with oxigen, mutually combine. 3. But no part 

 of the first class will combine with any part of the second. 

 4. The first class have no affinity for water. 5. The second 

 class, and most of the saline substances, do dissolve in 

 water. 

 Objection an- It will now be incumbent on me to obviate some objec- 

 swere . tions, which may naturally oppose what T have said ; and 



Union of alka- the most prominent is the union of the combustible bodies 

 lis and metallic ^ith the alkalis and metallic oxides. But this objection is 

 oxides with 1 /. 1 • 11 



combustibles; readdy answered ; for those combustibles, which enter into 



such a combination, really contain oxigen; they are sulphur, 

 phosphorus, and sulphuretted hidrogen. I think it suffi- 

 cient 



