is Mr. Davy’s Experiments on the 
I shall now resume the detail of the experiments that 
I have made, on the relative attractions of oxymuriatic gas 
and oxygene, for the metals of the fixed alkalies. I burnt 
a grain of potassium in oxygene gas, in a retort of green 
glass, furnished with a stop-cock, and heated the oxide 
formed, to redness, to convert it into potash : half a cubi- 
cal inch of oxygene was absorbed. The retort was ex- 
hausted, and very pure oxymuriatic gas admitted. The 
power, and in these instances procuring the metals in very small quantities only, 
I perceived no effervescence. When from five hundred to one thousand plates are 
used for producing potassium, there is a violent effervescence, and a production of 
hydrogene and sometimes of potassuretted hydrogene, connected with the formation 
of the metal. 
Potassium, brought in contact with red hot hydrat of potash, disengages abundance 
of hydrogene, and the whole is converted into difficultly fusible potash. 
327 grains of hydrat of potash that had been ignited, were made to act in a gun- 
barrel on 745 grains of iron turnings heated to whiteness. Some hydrogene was lost, 
and some hydrat of potash remained undecompoundcd, yet 225 cubical inches of in- 
flammable gas were collected, and 50 grains of potassium, and a large quantity of an 
alloy of potassium and iron formed, so that it is scarcely possible to doubt that nil the 
hydrogene produced from the decomposed hydrat of potash was liberated. 
Mr. Dalton conceives that there is an analogy between potassium and sodium, 
and the compounds of hydrogene with sulphur, phosphorus, and arsenic; but 
I am at loss to trace any similarity between sulphureted hydrogene, which is 
a gaseous body, soluble in water, and having acid properties, and a highly inflam- 
mable solid metal which produces alkali by combustion. Potassium might as well be 
compared to carbonic acid. Mr. Dalton considers the volatility of potassium and 
sodium as favouring the idea of their containing hydrogene; but they are less vola- 
tile than antimony, arsenic, and tellurium, and much less volatile than mercury. He 
mentions their dow specific gravity as a circumstance favourable to this idea. I have 
on a former occasion examined this argument, first brought forward by M. Ritter ; 
but it may .not be amiss to add, that if potassium is a compound of hydrogene and 
potash, hydrat of potash must contain an equal quantity of hydrogene, with the addi- 
tion of a light gaseous element, oxygene, which might be expected to diminish 
rather than to increase the specific gravity of the compound. Mr. Dalton states, 
jp. 488, that potassium forms dry hydrat of potash, by decomposing nitrous gas 
