portion, the ratio in four different experiments Ijeing nearly 

 as 28 volumes of ammonia to 23 of hydrogen. These results 

 were obtained by first drying the amalgam with bibulous 

 paper, then introducing it into a tube containing a little 

 mercury, closing the tube with the finger, agitating it for 

 some minutes with the enclosed air, opening the tube after 

 inversion in mercury, measuring the ammonia by absorbing 

 with water, and determining eudiometrically the hydrogen 

 mixed with the residual air. The amalgam was afterwards 

 described by Thenard, in his Tixdte de Chimie,^ under the 

 name of " ammoniacal hydride of mercury." 



It is interesting to observe that in 1816 Ampere,^ in the 

 passage where the now universally received views on the 

 constitution of ammoniacal compounds are first propounded, 

 refers to the amalgam. Speaking of the difiiculty of 

 assimilating the constitution of ammoniacal to metallic 

 salts, he remarks — ''• This difiiculty would disappear if we 

 admit that, just as cyanogen, although a compound body, 

 exhibits all the properties of the simple bodies which are 

 capable of acidifying hydrogen, so the combination of one 

 volume of nitrogen and four volumes of hydi'ogen which is 

 united to mercury in the amalgam discovered by M. See- 

 beck, and to chlorine in the hydrochlorate of ammonia, 

 behaves in all the compounds which it forms like the simple 

 metallic substances." This theory was more fully developed 

 by Berzelius and was soon generally received, except as re- 

 gards the amalgam, concerning which various conflicting 

 opinions were entertained. Daniell, j for example, speaks of 

 it as a mere mixture of mercury and gases resulting from the 

 cohesion of the mercury and the adhesion to it of the gases,- 

 and he cites the absorption of oxygen by melted silver as a 

 similar case. 



* Vol. II. p. 162, 3me ed. 



t Annates de Chiniie et de Physique^ II. 16, Note. 



% Chemical Philosoplcy^ p. 420. 



