406 PRIZE QUESTIONS. 
15. It is desirable that exact researches should be instituted respecting the 
distribution of plants and animals in the coal strata of different countries. 
16. A memoir of Savart, communicated as an extract in the Journal of the 
Institute, No. 313 and 314, by M. Masson, contains the account of experiments 
on the simultaneous movement of two pendulums. ‘The Society would wish 
these experiments to be repeated and explained, if their result be confirmed. 
17. Late researches on beats and the resulting sounds do not seem to lead 
necessarily to an abandonment of the principle of Daniel Bernouilli, of the coex- 
istence of small oscillations for vibrations, which are propagated in an indefinite 
medium. ‘he case is wholly different when the question relates to vibrations 
with fixed modes and centres in a circumscribed medium. The Society invites 
new researches, as well experimental as theoretical, on the resulting sounds and 
the vibrations of stretched cords and membranes which produce them by their 
combinations and their interference. 
18. It seems that the phenomenon, known as Porrets’s, of the electrical trans- 
lation of matter across a porous diaphragm, is not an isolated fact, but that by 
considering it in its relations with other phenomena it will be found to be a par- 
ticular case of a general action. New researches therefore are invited respect- 
ing this phenomenon, especially with reference to those of M. Hittorff, on the 
translation of elements in the electrolysis. 
19. Recent researches have evinced an important analogy between the con- 
ducting power of bodies for heat and for the electric current. ‘The substances 
compared in this respect were all good conductors of electricity. The Society 
desires researches on the conducting power as regards heat of certain isolating 
or slightly conducting substances, az glass, marble, &c., and a discussion of the 
results obtained, in reference to what has been disclosed by the remarkable 
researches of M. Gaugain respecting the conducting power and inductive capacity 
of such substances for electricity. : 
20. New experimental researches are requested respecting the interior friction 
or viscosity of liquids in movement, and on their friction against the walls of 
the channel or tube in which they are moving. It is particularly desirable 
that a viscid liquor, for instance a thick oil, should be experimentally studied 
under this point of view. 
21. The Society solicits further exact researches upon the remarkable phe- 
nomena of dissociation discovered by M. Sainte-Claire-Deville. 
For this year the following questions, whose term expires the first of January, 
1867, have been proposed : 
1. An exact determination of the heat produced by the combustion of the 
glycerides is desired. 
2. The fractional distillation and fractional precipitation, extolled as means 
for separating from one another bodies homologous in their mixtures, are, as 
such, very insufficient. The Society invites a’research for better means of ob- 
taining that result. 
3. It seems that the diminution of temperature in the successive strata of the 
atmospheric air is not equal under different iatitudes; it is desirable to have 
this point so interesting for meteorology elucidated by new researches. 
4. The Society wishes an illustrated memoir containing very exact micro- 
scopic researches on the formation and development of the egg in the ovary of 
fishes and birds. 
5. A monography as complete as possible of the lichens of the Netherlands. 
6. We possess very exact determinations of the density and of the dilatation 
of mixtures of ethylic alcohol and water by Gilpin, Gay Lussac, and M. von 
Baumhauer. Determinations not less exact are requested for mixtures of water. 
and methylie alcohol. 
7. We only know with sufficient exactness the density of very few bodies 
soluble in water which might not be found by the ordinary hydraulic balance 
