HEAT OF COMBINATION OF METALS IN FORMATION OF ALLOYS, 24% 
The experiments were made according to the method fully described 
in a paper by Dr. Galt, on “Heat of Combination of Metals,” com- 
municated to the Royal Society of Edinburgh, on March 7, 1898.! 
In each case of solution the nitrous products remained in the liquid, the 
vessel in which the solution took place being kept closed by a cork. The 
importance of this arrangement is illustrated by the following statement 
extracted from the paper just referred to :— 
“Tf the method of pouring the acid on the filings or of dropping the- 
filings into the acid had been adopted, a violent action would have 
occurred, and it would not have been pessible to prevent the loss of heat 
due to escape of fumes. But the plan adopted effectually got rid of this 
difficulty by the almost instantaneous projection of the bulb containing the 
filings to the bottom of the acid.? It was very interesting to watch the 
scouring effect in the bulb due to the chemical action ; the filings were aimost 
instantaneously expelled from it by the rapid evolution of gas, the removal 
being facilitated by the existence of the two apertures already described. 
The gentle rotatory motion given to the acid was kept up while solution 
was going on, and when it was complete the thermometer reading was 
again noted. The time required to effect solution was 50 to 55 seconds, 
and it was observed that complete solution and maximum temperature 
were reached about the same time.” 
Addition by the Chairman. 
The Committee has carefully considered an objection to the method of 
experiment which was suggested after the reading of the Report at the 
Dover meeting, to the effect that nitrous products evolved from the 
solution might be different in the cases of the solution of the mixture 
and the solution of the alloy. It seems not probable that even if gaseous. 
products had been allowed to escape, they would have been different in 
these two cases ; but as the whole nitrogenous products remained in the 
solution in each case, it seems scarcely possible that there can have been 
any final chemical difference in the solutions. As, however, the question 
has been suggested, a chemical investigation of the solutions in the two 
cases might be interesting. K. 
Addition by Dr. Gladstone. 
This suggestion of the Chairman seems to me most important, and one 
that ought to be carried out, as there is reason to believe that the chemical 
products in the two solutions would be different. os Ehe G, 
Addition by Professors FitzGerald and Lodge. 
The above report was drawn up by Dr. Galt, and though we consider 
it most interesting, and have reason to believe that if the experiments 
were repeated the results would not be very different, yet, as it has been 
suggested that the chemical products resulting from actions on the mixed 
metals and on the alloy might be different, we do not feel justified in con- 
cluding that the heat of combination of the metals can be safely deduced 
from these results in the simple way suggested. G. F. F.-G., O. J. L. 
' Proc. RS.H. vol. xxii., 1898, p. 137. 
* Andrews'’s Scientific Papers, p. 214. Every chemist is familiar with the violent 
action of nitric acid on zinc and copper, and the abundant evolution of gas which 
accompanies it. But the facility with which the gases miy be condensed by the 
acid solution is probably not so generally known, and whcn the experiment is made 
for the first time it cannot fail to excitessurprise. 
