ON THB METALS OF THE ALKALIS. $$ 



tain time to be nearly stationary. At this period let the 

 gaseous residuum be measured, and suppoi^f it to be equal, 

 for instance, to two thirds of the volume of hidrogen em» 

 ployed, it will be concluded, that one third of the hidroj^en 

 has l)een absorbed by the potassium. And, in fact, it may 

 be expelled from it immediately, by heating the potassium 

 snffitiently in the same jar in which the experiment has 

 been made, and which is then full of mercury. 



"Thus we find, that potassium absorbs a quantity of 

 hidroijen, which is equivalent nearly tp a fotirth of what it 

 gives out with water. We have repeated this experiment a 

 great number of times,, the result has always been the same. 

 It is certain then, that a solid hydruret of potassium exists. ^ ^ ^ 



The properties of this hydruret may be seen in the Bib, brit, 

 as above quoted.*" 



"Mr. Davy says, that potassium absorbs more ammonia- Potanlum 

 cal gas dried by lime, than of common ammoniacal gas, in ^^^ ^o,^diy 

 the proportion of id to 12*5. We have always observed on ammoniaca 

 the contrary, that the absorption of these two gasses is per- moist ^'^ 

 ceptibly the same with an equal quantity of potassium, if 

 the temperature be the same; as we have already shown in 

 the Bib. brit. What Mr. Davy considers as potash is 

 already, according to us, an ammoniuret. 



** Mr. Davy says, that i he ammoniuret. made with »n)mo- Ammoniuret 

 piacal gas and potassium, does not give out, as we have ad« g,y^Qu\'*^™^ 

 vanced, the 0-6 of ammoniacal gas it contains; narr;t'ly. 0*4 ''rj^nionia un- 

 npt decora posedj^^nd 0-2 decomposed; or at least that thetie ^^™^'"**^ 



♦ ** !t is iu tlie foirn of a gray powder, which has not a metatHc ap- Properties of 

 pearancc. Ii effervesc s briskly with water, and gives out abdut one ^^^ hidruret of 

 fourth more of hidrofeu, than the metal it contains is capable of giving P**'**"^'""*- 

 out. Placed in contac; with mercury in the cold, it is giadually decom- 

 posed j, an amalgam of this metal is formed, and all the hidroeen, to 

 which it owed its pulverulent state, is evol-e-?. if heated, its detomr 

 position by niercurj is almost instantaneous, and no more hidrogen gas Lr 

 evolved than wl«en cold, in fine, hea'ed to an obscure red, it resumes 

 the metallic anpearance, and also evolves all the hidrogen, ttthich the " * ♦% 



metal had absorbed." Ann. de Chim. vol. LXXII,p 266. . -i '". \. '^ 



■f Messrs. GayrLussac and ThenarHsay, in the ]ilace referred to, thatC' * * *' 



temperature somewhat elevated expels a great deal of ammonia frv)m the 

 olive coloured subitarice; and hence th quantity of ammonia absorbed 

 by the metal is verj variable, according to the temperature employed. 



results 



