SCIENTIFIC SUMMARY. 
483 
M. Claudet called attention to an improved instrument which is used to 
equalise the focus of a lens on different planes. Sir David Brewster made 
some remarks on the enamel photographs of Mr. McCraw, of Edinburgh, 
and M. Claudet read a short communication on the result of some experi- 
ments with non-achromatic lenses of rock-crystal and topaz, the results of 
which, he said, were very promising, which experiments he had been in- 
duced to make by the theory Sir David Brewster published many years 
since. In Section B, Mr. J. Spiller, F.C.S., read a paper on certain new 
processes in photography. These processes were the various modifications 
of Mr. Woodbury’s, micro-photosculpture, photolithography as practised in 
the Boyal Arsenal at Woolwich, and a process of printing on silk, satin, or 
cambric, practised by Mr. H. B. Pritchard, of the War Department. 
Action of Light on Honey. — M. Scheibler has attributed the crystallisms of 
honey to the photographic action of light, and thus explains why bees 
carefully exclude light from their hives, as, if light obtained access, the 
syrup on which the young bees feed would, by becoming more or less solid, 
seal up the cells, and probably prove fatal to the inmates of the hive. 
PHYSICS. 
Action of Glass Rods in Liberating Gases from Solution. — Mr. Chas. Tom- 
linson’s researches on this point show that the phenomena of liberation of 
the gas depend, not on any peculiar action in air or gas, but on whether the 
rods are clean or not. The theory that he proposes to substitute rests on the 
distinction between a chemically clean solid and one that is clean in the 
ordinary sense of the word. If the solid be chemically clean, there is perfect 
adhesion between it and the solution, and there is no liberation of gas ; if the 
solid be not chemically clean, then the adhesion is imperfect, and there is a 
separation of gas. If the water is not attracted by the solid, the gas is ; for 
although the rod may not be clean enough for water to adhere to it, yet gas 
will adhere to a dirty or a greasy rod. If the rod be made chemically clean, 
it soon ceases to be so by exposure to the air ; and this circumstance, accord- 
ing to Mr. Tomlinson, has led the numerous writers on supersaturated 
solutions of salts into error as to the action of nuclei , &c., in inducing crys- 
tallisation. If the nucleus be chemically clean, the solution wets it perfectly, 
and there is no separation of salt from the water ; if the nucleus be not 
chemically clean, there is separation. — Vide Philosophical Magazine , August. 
Lnfluence of Capillary Action on Chemical Decomposition. — M. Becquerel 
continues his researches on the action of capillarity in chemical decomposi- 
tions. In his third communication he gave a new set of illustrations of the 
law already expressed by him. He stated that the phenomena described by 
him in his earlier papers are due to the influence of three agencies — affinity, 
capillarity, and electricity. To demonstrate the intervention of electricity, 
M. Becquerel has made the following experiment: he immersed his split 
bell-glass, containing nitrate of copper, in a second bell containing a solution 
of monosulphide, as in the first experiments ; then he dips the two extremities 
of a silver wire, one into the nitrate, and the other into the monosulphide. A 
YOL. YI. NO. XXY. M M 
