114 COMBINATIONS Of OXIMCRIATIC CJA8 AND OXIGEN. 



ipore fully, than I have yet attempted, the nature of the 

 combinations of potassium and sodium with oxigen, and of 

 potash and soda with water. 

 When this Is I have stated in the last Bakerian Lecture, that potassium 



na^UiTmetal ^^^ sodium, when burnt in oxigen gas, produce potash and 

 oxided. soda in a state of extreme dryness, and very difficult of 



fusion. In the experiments from which these conclusions 

 are drawn, as I mentioned, I used trays of platina, and 

 finding that this metal was oxidated in the operation, I 

 heated the retort strongly, to expel any oxigen the platina 

 might have absorbed, and, except in cases when this precau- 

 tion was taken, I found the absorption of oxigen much 

 greater tlmn could be accounted for by the production of 

 Potassium and the alkalis. In all cases in which I burnt potassium or 

 sodium burned sodium in common air, applying only a gentle heat, I found 

 in common it,- i i i ^ -i i 



air produce that the tirst products were substances extremely lusible, 



brown, fusible ^^^^ of a reddish brown colour, which copiously effervesced 

 * in water, and which became dry alkali, by being strongly 

 heated upon platina in the air; phenomena, which, at aa 

 early period of the inquiry, induced me to suppose that they 

 were protoxides of potassium and sodium. Finding, in 

 subsequent experiments, however, that they deflagrated 

 with iron filings, and rapidly oxidated platma and silver, I 

 suspended my opinion on the subject, intending to inves- 

 tigate their nature more fully. 



, . . Since that time, these oxides, as 1 find by a notice in the 



•wnicii are per- ^ *' 



•xides. Moniteur for July $th, 1810, have occupied the attention of 



Messrs. Gay-Lussac and Thenard; and these able chemists 



have discovered, that they are peroxides of potassium and 



sodium, the one containing, according to tliem, three times 



as much oxigen as potash, and the other 1*5 times as much 



as soda. 



When they I have been able to confirm in a general way these rntcr- 



are formed on estinsT results, though I have not found any means of as- 



jneuUicsub- ? . , , .i .-^ r> • . • i • 



itances these certaimng accurately the quantity ot oxigen contamed m 



are always ox- these pew oxides. When they are formed upon metallic 

 w' '^ * substances, there is always a considerable oxidation of the 



metal, even though platina be employed. I have used a 

 platina tray lined with muriate of potash, that had been 

 fused; but in this caKe, though I am inclined to believe 

 ^ that 



I 



