40S On defmite Proportions^ 



Oxygen than Davy found, although most of the causes of 

 error tend to lessen the apparent quantity of oxygen. 



1.) I collected several portions of the amalgam, and 

 weighed them before and after the extraction of the po- 

 tassium. The potass obtained was mixed together and 

 saturated wiih muriatic acid, the excess of which was eva- 

 porated in a small glass vessel, and ihe salt, tojiether with 

 the washings of the glass, was dried in a sma'l golden cru- 

 cible, weighing about three grammes, and then melifd and 

 weighed in the crucible. The whole ot the potassuuTi had 

 weighed '4575 gr. and the melted muriate of potass 'SCys. 

 Now the muriate of potass contains 6i*19 per cent, of 

 potass, consequently the '5675 gr. answer to -SSfiS gr. of 

 pure potass; and potass consists, according to this experi- 

 ment, of 82' 166 of potassium, and 1 7*834 of oxygen. 

 Some chemists have objected to this mode of determination, 

 that the fused salt miiiht possibly still contain some water. 

 But nor to mention, that the calculation for this salt gives 

 almost the same quantity oF potass, (see Lard. i. kem. I. 

 399.) it is well known that in a melting heal neither the 

 muriate of potass nor that of soda is altered by charcoal, 

 by phosphorus, or by iron, which would necessarily happen 

 ii they contained water, at the expense of which these 

 combustible bodies would be oxygenized. 



2.) The different operations of weighing might have oc- 

 casioned inaccuracies, which might be singly unimportant, 

 but of material consequence when added together. I there- 

 fore repeated the same experiment with a single pojrti<m 

 of amalgam, which weighed 30*0775 gr. It gave, by treat- 

 ment with water, • 1275 gr. of potassium ; and this, satu- 

 rated with muriatic acid, boiled, and melted, '25 gr. of 

 muriate of potass, containing ']60 gr. of pure potass: 

 whence we have 80 of potassium to 20 of oxygen. 



3.) The difference of these results being very consider- 

 able, I repeated ihe experiment with a greater quantity of 

 a hardened amalgam, which weighed 67 '003 gr. It lost 

 •32 in water, and gave -fiOS of fused muriate of potass, 

 which is equivalent to -39027 of pure potass. Hence 100 

 parts of potass CDutain S-2 of potassium and 18 of oxygen. 



According to these experiments, 100 parts of potass 

 seem to contain about 18 parts of oxygen, and 82 of po- 

 tassium. And if we examine this result by the rules in- 

 vestigated and developed in tiie first part of this essay, we 

 shall find ir very correctly confirmed. The sulphate of 

 potass consists, according to Pucholz's experiments on 

 precipitaiiou (Soberer x. 396) of 45 '34 of the acid and 



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