5 



the amalgam may, after washing, be transferred into the 

 acid, the adhering water will nevertheless take up some 

 more ammonia from the continuously decomposing substance 

 while the hydrogen escapes. 



It must be observed that Davy himself appears to have 

 found a difficulty in obtaining consistent results, for he does 

 not seem to have ever entirely satisfied himself as to the 

 proportions of the two gases. These are the words in which 

 he sums up his observations : — " As it does not seem possible 

 to obtain an amalgam in an uniform state, as to adhering 

 moisture, it is not easy to say what would be the exact ratio 

 between the hydrogen and ammonia produced, if no more 

 water was present, than would be decomposed in oxidating 

 the basis. But in the most refined experiments which I 

 have been able to make, this ratio is that of one to two ; 

 and in no instance in which proper precautions are taken, 

 is it less ; but under common circumstances often more. If 



this result is taken as accurate ", &c.* 



This statement of Davy's being apparently the only 

 authority for the assertion that the decomposing amalgam 

 gives ofi*the gases in atomic proportions, and yet being in con- 

 flict with Gay Lussac and Thenard's results, it appeared to me 

 desirable to attempt to obtain more exact determinations. 



I used amalgam prepared by electricity in the manner 

 described by Landolt. 



A simple mode of eliminating the disturbing eff*ect pro- 

 duced by the attraction of ammonia for moisture suggested 

 itself. A U-shaped glass tube was provided, 

 open at both ends, about 1-4 centimetres in 

 diameter and having its shorter limb 40 centi- 

 metres long. At the bottom of the longer 

 limb, just above the bend, there was an outlet 

 tube to which was attached a piece of caout- 

 chouc tubing closed by a pinch-cock. Mer- 

 <^ cury was poured into the tube until it filled 

 * Bakei'ian Lecture, 1809. 



