172 MR. R. ROUTLEDGE ON THE 



electrically prepared substance gave off the gases in quite 

 another proportion, the ratio in four different experiments 

 being nearly 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 con- 

 taining a little mercury, closing the tube with the finger, 

 agitating it for some minutes with the enclosed air, open- 

 ing the tube after inversion in mercury, measuring the 

 ammonia by absorbing with water, and determining eudio- 

 metrically the hydrogen mixed with the residual air. The 

 amalgam was afterwards described by Thenard, in his 

 'Traite de Chimie'*, under the name of "ammoniacal 

 hydride of mercury." 



It is interesting to observe that in 18 16 Ampere f, in 

 the passage where the now universally received views on 

 the constitution of ammoniacal compounds are first pro- 

 pounded, refers to the amalgam. Speaking of the diffi- 

 culty of assimilating the constitution of ammoniacal to 

 metallic salts, he remarks — " This difficulty would disap- 

 pear if we admit that, just as cyanogen, although a com- 

 pound body, exhibits all the properties of the simple bodies 

 which are capable of acidifying hydrogen, so the combina- 

 tion of one volume of nitrogen and four volumes of hydro- 

 gen which is united to mercury in the amalgam discovered 

 by M. Seebeck, 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 regards the amalgam, concerning which 

 various conflicting opinions were entertained. DaniellJ, 

 for example, speaks of it as a mere mixture of mercury 

 and gases resulting from the cohesion of the mercury and 



* Vol. ii. p. 162, 3me edit. 



,t Annales de Chimie et de Physique, ii. p. 16 (note). 

 { Chemical Philosophy, p. 420. 



