the Decomposition of the Earths, &c. 2 1 9 



Something has been separated from them which adds to 

 their weight ; and whether it be considered as oxygen, or as 



water, 



T have seen an account of some very curious experiments of M. M. Gay Lus- 

 *ac and Thenard, (in number 148 of the Moniteur, for 1808, which I have 

 just received,) from one of which thev have concluded," that potassium may 

 be a compound of hydrogen and potash." 



These gentlemen are said to have heated potassium in ammonia, and found 

 that the ammonia was absorbed, and that hydrogen gaa equal to two-third* 

 of its volume appeared, and that the potassium by this process had become of 

 a grayish-green colour. By heating this grayish-green substance consider- 

 ably, two.-fifths of the ammonia were again emitted, with a quantity of hydro- 

 gen and nitrogen corresponding to one-fifth more;and by adding water to the 

 mixture,and heating it very stronglyagain, they obtained the remainderof the 

 ammonia, and nothing but potash was left. 



In these complex processes, the phenomena may be as easily explained on 

 the idea of potassium being a simple, as that of its being a compound, sub- 

 stance; nor when the facts that have been stated in this paper, and those 

 about to be stated, are considered, can the view of these distinguished che- 

 mists, as detailed in the notice referred to, be at all admitted. 



Potash, as I have found by numerous experiments, has no affinity for am- 

 monia, for it does not absorb it when heated in it ; it is net therefore (allow- 

 ing their theory) possible to conceive that a substance having no attraction 

 for potash, should repel from it a substance which is intimately combined with 

 it, and which can be separated in no other way. 



A part of the hydrogen evolved in their experiment, raay be furnished by 

 xvater contained in the ammonia; but it is scarcely possible that the whole of 

 it can be derived from this source, for on such an idea the ammonia must con- 

 tain more than half its weight of water. There is however no evidence that 

 the whole of the hydrogen may not be furnished by the decomposition 

 of the volatile alkali itself. Potassium in its first degree of oxygenation may 

 have an affinity for nitrogen, or potassium may expel a portion of hydrogen at 

 the moment of its combination with ammonium ; and as the whole of the am- 

 monia cannot be regenerated without the presence of water, hydrogen and 2 

 little ox vge'n may be furnished tp the remaining elements of the ammonia, 

 from the water, and oxygen to the potassium. 



Even before the conclusion was formed, that a metallic substance is decom- 

 posed in this experiment, it should have been proved that the nitrogen had 

 not been altered. 



That mere potash, combined with hydrogen, cannot form potassium, is, ( 

 think, shown by an experiment which 1 tried, in consequenceof the important 

 fact lately ascertained by M. M. Gay Lussac and Thenard, of the deoxidation 

 of potash by iron. 



An ounce of potash was kept in ignition for some time in an iron tube, 

 ground into a gun barrel in which one ounce and a half of iron turnings 

 were ignited to whiteness ; a communication was opened, by withdrawing a 



wir? 

 2 



