212 Mr Monckman, Note on some Experiments. [Mar. 12, 
It is evident, therefore, that in order to commence in a clean 
smooth glass or porcelain vessel, a layer of crystals must be formed 
above the watér-line. This is done either by the evaporation of 
the film left after shaking, or by the lowering of the whole surface 
by the same means, when a line of salt is left at the edges. 
This line of salt then acts as a rough surface, and as it is not 
closely packed there are passages between the crystals which act 
as irregular capillarytubes. In the former case the thin film of liquid 
will soon evaporate and the creeping commence, while in the latter 
more time will be required. Hence the irregularity in the starting. 
(2) On the action of Acetone on the Ammonium Salts of fatty 
acids in presence of dehydrating agents. By Dr RUHEMANN and 
D. J. CARNEGIE, B.A., Caius College. 
By means of this reaction the authors obtained a base of 
the formula C,H,.N which had previously been obtained by Heintz 
by quite a different reaction. From their experimental results the 
authors conclude that this base is an unstable hydrogenised 
pyridine body; but their attempts to reduce it to a well-defined 
member of the pyridine series have so far been unsuccessful. 
(8) On the reduction of solutions of ferric salts to ferrous salts 
by certain metals. By D. J. CARNEGIE, B.A., Caius College. 
Certain metals (e.g. Zn, Pb, Fe, Cu) in a state of very fine 
division almost instantly reduce ferric salt solutions. The author 
develops a rapid method for reducing ferric salts prior to titration 
with the usual volumetric reagents. Occluded hydrogen has a 
similar though slower reducing power; and the nature of the metal 
by which the hydrogen is occluded is a factor in the reduction. 
(4) On the relation between the contraction of volume and the 
heat developed on mixing certain liquids. By S, SKINNER, B.A., 
Christ’s College. 
The author, by calculation from known data, shewed that the 
contraction on mixing liquid hydrochloric acid with liquid water 
bore the same ratio (within 3 per cent.) to the heat which would 
be developed on mixing liquid hydrochloric acid and liquid water, 
in solutions varying in strength from 40 to 4 per cent. of the acid. 
He accounted for this by the hypothesis that some of the mole- 
cules of the acid form compound molecules with those of water. 
If this be true, the number of these compound molecules would be 
greater the less the acid present in proportion to the water. He 
shewed this on his hypothesis to be the case. 
He also examined the cases of mixing liquid ammonia with 
liquid water, and liquid acetic acid with liquid water. 
