36^ 



ON THE ALKALINE METALLOIDS. 



But potassium 

 may be oxided 

 in diflFereut de- 

 grees. 



This might 

 have aifected 

 the result, 



though it did 

 not appear to 

 be the case. 



The experi- 

 ments favour 

 the opinion, 

 that potassium 

 is a compound 

 of a. metal with 

 bidrogen. 



eminent chemists. But, after taking every precaution io 

 guard against any source of fallacy, I have been able to ob- 

 tain no other result. If the product of the combustion of 

 the potassium were the real alkali, 5 grains of it ought to 

 have neutralized 162 of the above acid, since 5 grains of 

 ignited potash, containing at least 14 per cent of alkali, neu- 

 tralized 139 grains. 



The only circumstance which I can discover, as leaving 

 any room for doubt, is that of the different degrees of oxi- 

 dation, of which potassium is susceptible. There is reason 

 to believe, that a compound may be obtained at a lower de- 

 gree of oxidation than potash ; and from the more recent 

 experiments of Gay-Lussac and Thenard, the general re- 

 sult of which has been stated by Mr. Davy, it farther ap- 

 pears, that another compound, in which the potassium is 

 more highly oxidated than it is in potash, may be formed. 

 This last substance, they have stated, contains three times 

 more oxigen than potash does ; this excess of oxigen is ex- 

 pelled by exposure to a red heat, or when the product is 

 dissolved in water, it is disengaged. If this substance had 

 been the one operated on in the above experiments, it 

 might give rise in part to the apparently equal alkaline 

 strength of the potash formed by the combustion of potas- 

 sium, and ignited potash ; as a given weight of it would con- 

 tain less real alkali than when this excess of oxigen was not 

 present. But the circumstances connected with the experi- 

 ment lead me to believe, that no important errour from this 

 cause could have operated. The product of the combustion 

 of the potassium was always kept for some timcat a red heat, 

 before it was operated on, by which, according to Gay-Lussac 

 and Thenard, this excess of oxigen is expelled ; and except 

 in one experiment no effervescence was perceived on dissolve, 

 ing it in water. 



If these sources of errour have not operated, and the ex- 

 periments be correct, they appear to me to support the 

 opinion I have advanced with regard to the nature of potas- 

 sium. Were it the real base of the alkali, forming it when 

 combined with oxigen, the compound thus formed must 

 be superior in alkaline strength to common potash, which 

 contains so considerable 4 proportion of combined water. 



Excluding 



