1854.] OF THE ROYAL INSTITUTION. 417 
base, or subject of the combination, between the two bodies whose 
actions are opposed ; and that the proportions of this partition are 
determined, not solely by the difference of energy in the affinities, 
but also by the difference of the quantities of the bodies,— by their 
physical condition,— and by that of the combinations capable of 
being generated. These views did not meet with a favourable 
reception at the time of their promulgation; and the attention of 
chemists had been drawn away from the subject until within these 
last few years, when Malaguti, Bunsen, Debus, and Williamson, have 
published investigations bearing upon the point. The Lecturer then 
stated that before any of these papers had appeared, he had been 
thinking of and performing some experiments upon the subject in 
question, and that he was still continuing them. 
After a few experiments illustrative of ‘‘ Chemical combination ” 
and of ‘ Elective Affinity,” others were introduced to show how 
easily this latter phenomenon was affected by circumstances. Thus 
ammonia will displace alumina from a solution of the sulphate, but 
on the other hand, alumina will displace ammonia when heated with 
the solid sulphate of that volatile base; whilst if solutions of chloride 
of aluminum and sulphate of ammonia be mixed and evaporated, 
crystals of the double sulphate, ammonia-alum, will appear. There 
were on the table two white salts; the one had been carbonate of 
baryta, but by boiling with excess of sulphate of potash, it had been 
converted into the sulphate; the other had been sulphate of baryta, 
but by long continued boiling with much carbonate of potash, it had 
suffered the opposite change into the carbonate. The Lecturer then 
stated that so great is the influence exerted by these various circum- 
stances, that some have doubted whether there be a true “ elective 
affinity ;”” he however believed that after making every allowance for 
known causes there is still a residuary phenomenon to which that 
name is the most appropriate. Allowing then, with Bergmann, 
that relative degrees of affinity exist, the question arises:— Is 
Berthollet’s law also correct? It is very difficult to arrive at a 
satisfactory answer, since it is almost impossible to eliminate 
other influences. Several reactions, however, were mentioned 
as tending to show that there is some truth in the law :— 
for instance, the solution of gold in hydrochloric acid upon the 
addition of nitrate of potash. The experiments of Bunsen on 
mixtures of carbonic oxide and hydrogen, exploded with a quantity 
of oxygen insufficient for complete combustion ; and those of Debus 
on the precipitation of mixed hydrates of lime and baryta by carbonic 
acid, were explained ; as also the remarkable fact noticed by both, that 
the resulting products were always in certain atomic proportions to 
one another. But in both these cases the first products of the 
chemical action are removed at once from the field: it is quite 
another case when they remain free to act and react on one another. 
Supposing they all remain in solution, the requisite is fulfilled ; but 
how are we to know what has then taken place? Malaguti thought 
