4 
Grove,* in 1841, made a few experiments on the amalgam, 
and advanced the idea that it is a chemical compound of 
mercury and nitrogen, merely swelled up with hydrogen. 
In 1864, Dr. Wetherillf performed several ingenious 
experiments on the amalgam, without however attempting 
any quantitative estimate of its composition. He concludes 
that it is not an alloy of mercury and ammonium, and that 
the swelling up of the mass is due to the retention of gas 
bubbles by virtue of some unexplained action which he 
somewhat vaguely refers to catalysis. 
In the Annalen dev Ghemie u. Pharmacia for 1868^ is a 
paper by Landolt, in which, after pointing out the discord- 
ance of the quantitative results obtained by Davy, and by 
Gay Lussac and Thenard, he describes a method by which 
he attempted a new determination of the relative quantities 
of ammonia and hydrogen. He prepared the substance from 
a solution of sal-ammoniac, separated from the mercury, 
which formed the negative pole, by a porous cell. The 
amalgam, when removed from the circuit, was washed in a 
stream of water to get rid of the adhering solution of sal- 
ammoniac, which always contains free ammonia. It was 
then immediately plunged into dilute hydrochloric acid of 
known strength, and the hydrogen evolved was received in 
a graduated cylinder placed over it, while the ammonia was 
estimated by determining the amount of unneutralised acid 
in the liquid. Two experiments gave results corresponding 
respectively to 2T5 and 2 - 4 volumes of ammonia to 1 of 
hydrogen. These figures of Landolt’s cannot be considered 
satisfactory, neither nearly agreeing with each other, nor 
approximating to the ratio 2 : 1 sufficiently closely to justify 
his conclusion that they “completely confirm the results for- 
merly obtained by Davy.” Indeed Landolt points out a 
serious defect in his process, namely, that however rapidly 
* Phil. Mag., United Series, yoI. xix., p. 97. 
f Silliman’s Amer. Journal [2], xl., 160. 
X Supp. Bd., yi., p. 316. 
