= a 
* 
pS 
il : Dr. Hare on the Salt Radical Theory. 
that a mere liability to combine with these elements, endows 
them with a power to combine with other elements, of which 
power they otherwise would have been destitute. Liebig as- 
cribes to hydrogen, not only the “action of presence,” but an 
“action of absence” likewise. According to him, the halogen 
bodies owe their power of entering into union with metals, to the 
| hydrogen which they contain, not only when the element is pres- 
‘ent, but to their susceptibility of uniting with it, whether retro- 
- spectively or prospectively. Let us see whether the phenomena 
on which these startling conclusions rest, are not susceptible of a 
more rational explanation. 
18. When any radical unites in several equivalent proportions 
with any one electro-negative body, it will usually unite in the 
same proportions with other electro-negative bodies. This isina 
great measure exemplified in the case of the oxides, sulphides 
and chlorides of iron; the oxides, sulphides and chlorides of 
tin and antimony. In like manner, the proportions in which 
oxygen enters into union with phosphorus and with arsenic are 
the same: also for every oxide of mercury we have a correspond- 
ing sulphide and chloride. But in some instances we have oxides 
of which there are no corresponding chlorides with the same rad- 
ical. Thus in the instances’ of the metals potassium, sodium, 
calcium, barium and strontium, we may have peroxides but not 
perchlorides. Whenever the metal can form a perchloride, its 
peroxide, on due contact with the chloride of hydrogen, (mu- 
riatic acid,) is resolved into water and a perchloride. But when 
the metal is incapable of forming a perchloride like those above 
mentioned, peroxides are not convertible into perchlorides. 
19. According to my apprehension, during the reaction of oX- 
ides with hydracids, so called, the hydrogen and oxygen only 
assist, by getting each other out of the way. In most instances, 
in which a chloride is generated by the meeting of an oxide with 
the chloride of hydrogen, it may be produced ‘by presenting the 
metal to gaseous chlorine, with heat, if not without. 
20. With respect to the peroxides of the metals of the alka- 
lies and alkaline earths, it has been stated that the law here enul- 
ciated does not prevail; and I think it must be evident that the 
quantity of chlorine in the resulting chloride, is dependent solely 
on the affinity between chlorine and the metal. The hydrogen 
may resist this affinity when oxygen does not cooperate, as when 
