408 Experiments on the Combinations of ' 
I shall now resume the detail of the experiments that I 
have made, on the relative attractions of oxymuriatic gas 
and oxygen for the metals of the fixed alkalies. I burnt a 
grain of potassium in oxygen gas, ina retort of green glass, 
furnished with a ‘stop-cock, and heated the oxide formed, 
to redness, to convert it into potash: half a cubical inch 
of oxygen was absorbed.) The retort was exhausted, and 
very pure oxymuriatic gas admitted. The colour of the 
potash instantly became white, and by a gentle heat the 
whole was converted into muriate of potash: a cubical inch 
and 2 of oxymuriatic gas were absorbed, and exactly half a 
cybical inch of oxygen generated. The barometer during 
this operation was at 30°3, the thermometer at 62 Fahren- 
heit. JT made several experiments of the same kind, but 
this is the only one on which I can place entire dependence. 
When I attempted to use larger quantities of potassium, 
the retort usually broke during the cooling of the glass, and 
it was not possible’to gain any accurate results in employ- 
ing metallic trays. The potassiam was spread into a thin 
plate, and of course was much oxidated before its admission 
into the retort, which rendered the absorption of oxygen a 
little less than it ought to have been. “In the are = 
| ‘heate 
nected with the most refined departments of chemical philosophy, and with 
so many new objects ‘of research; additional facts cannot be wholly devoid 
of use and-application! iid 
Mr. Dalton, in the second volume of the work which he:entitles 4 New 
System of Chemical Philosophy; of which he has had the goodness to send 
me a copy, has, I'find, in’ his first pages, adopted the idea that potash and so~ 
da are metallic oxides / Hurin'the latter pages has considered them as simple 
bodies, and the metals formed from them'as compounds of potash and soda 
with hydrogen?’ He has given'no factsin*favour of this change in his opi- 
nion: his pringipal argimetit' js founded ‘upon the process in which I first 
obtained ‘potassium, ‘ Conimon “potash is a hydrat: when oxygen is pro- 
cured from this’ by Voltaic electricity at one surface, and potassium at the 
other surface; Mr, Dalton, conctiving that apts og arises from the wa- 
ter, states that the hydrogen" of the! water must combine with the potash to 
form potassium.” ! Itis evident, that adopting such’a plan of reasoning, lead 
or copper thight be proved ‘td! be hydrurets of their oxides; for when these 
metals are revived from theifaqteous acid solutions, oxygen is produced at 
the positive surface; and no hydrogen at the negative surface. 
In my first experiments for producing potassium and sodium, I used a weak 
power, and in these instances procuring the metals in very small quantities 
only, I perceived no effervescencé.’ Whén from five hundred to one thou- 
sand plates are used for producing potassium, there isa violent effervescence, 
and a production of hydrogen and sometimes of’ potassuretted hydrogen, 
connected with the formation f the metal : 
Potassium brought'in contact with’ red ‘hot hydrat of potash, disengages 
iden A of hydrogen, and the whole is converted into difficultly fusible 
otash. = 
t 827 grains of hydrat’ of potash that had been ignited, were made to act 
in a gun-barrrel on 745 grains of iron turnings heated_to whiteness. Some 
hydrogen was lost, and some hydrat of potash remained undecompounded, yet 
225 
