i 30 COMBINATIONS OF OXIMUUIATIC ACID AND METALS.' 



lead was well washed and dried, and heated to dull redness 

 for a quarter of an hour in a platina crucible : by this treat- 

 fOxideof lead") ™^"' ^^^ ^^^® carbonic acid was expelled j the remaining yellow 

 oxide weighed 1077 grains, and it dissolved in muriatic acid 

 without effervescing, and without affording any residue of 

 brown oxide. Hence, the yellow oxide of lead appsj^^rs to con- 

 tain 7' 15 per cent of oxigen. And this proportion of oxi- 

 gen in the oxide compared with that of chlorine in plumbane, 

 lead being as 97'2, appears to be in the ratio of "J'S to 33'8, 

 instead of that of \5'Q the estimate of Klaproth, or of 11 '2 

 the estimate of Dr. Thompson to 33"8. Klaproth might have 

 been misled by considering the hydrated oxide as a true white 

 oxide free from water, 

 of antimony; According to Mr. Proust, the peroxide of antimony contains 

 f Oxides of an- ^^ per cent of oxigen, and the protoxide 18*. I have 

 timony.) repeated this chemist's experiments ; my results, in which the 



peroxide is concerned, agree with his j but there is not the 

 same concordance in those relating to the protoxide. The 

 protoxide I used was either prepared by the decomposition of 

 the butter of antimony, or of the sulphate, by a boiling solution 

 of carbonate of potash. This oxide, in its purest state, I have 

 always found, as Mr, Proust describes it, of a light fawn colour 

 before fusion, and afterward in mass of a gray colour, and of 

 a radiated crystalline texture. 100 grains of it that had been 

 fused were heated in the state of powder with strong test 

 nitric acid in a platina crucible : when nitrous gas ceased to be 

 produced, the excess of nitric acid was expelled by a gentle 

 heat, and the oxide was heated to dull redness 3 the increase 

 of weight after this was equal to i0"4 grains : nitric acid was 

 again added, and the process repeated, but without any alte- 

 ration of weight being produced. Hence, as the peroxide con- 

 tains 23 per cent, the protoxide seems to contain 15 per cent 5 

 which proportion of oxigen very nearly agrees with that of 

 chlorine in the butter of antimony; for, antimony being as 

 425, the former is to the latter as ']-5 to 34'6, instead of 33*6. 

 I put some confidence in this estimate of the proportion of oxi- 

 gen in the protoxide, not only on account of its agreement 

 with the analysis of the butter of antimony, but because it 

 was confirmed on the repetition of the experiment. 



* Journal de Pliysiq^ue, Tom. I.V, 



Klaproth 



