266 PROCEEDINGS OF THE SOCIETY OF 
mose of gases in traversing porous earths. This experiment evinces that if, 
when a current of hydrogen is traversing a tube of baked earth, we stop the 
current, there is a vacuum produced in the apparatus, which can be only attri- 
buted to the circumstance that a portion of the hydrogen passes through the 
sides of the porous tube. At the same time a certain quantity of atmospheric 
air is mixed with the gas remaining in the apparatus. 
M. Antoine communicated new researches on the combustible part of the gas 
of the fumarolles of Tuscany. Jt is composed in variable proportions of the 
marsh gas and protocarbonated hydrogen of double the volume. He con- 
cluded with some gencral considerations respecting the absorption of gases. 
From his experiments it results that the complete solution of the gases, on which 
liquid reactives exert a special action, depends on the mass of the absorbent 
body and on the extent and duration of the contact. M. dela Rive announced 
that M. Schénbein, who has been long occupied with the isolation of antozone 
or positive oxygen, has arrived at the desired result by the trituration of fluor- 
spar in water. 
M. Marcet gave an account of a memoir, published in America by MM. Elliot 
and Scherer, on the purity of zinc. The purest of all is that of Old Mountain, 
and next the zine of Pennsylvania. On this subject, M. de la Rive announced 
that M. Deville has sueceeded in obtaining very pure zinc by means of distilla- 
tion, and that he has, moreover, discovered a process for procuring it in a very 
pure state from the sulphate of that metal. M. Favre referred to some new 
experiments of M. H. Deville for the production of artificial minerals. He has 
succeeded in producing fluoride of aluminum and staurotide, and has ascer- 
tained that a very small quantity of the fluoride of silicon will mineralize a very 
considerable mass of base. M. P. Morin communicated an abstract of an analy- 
sis which he has made of water from the fountain of Guillot at Evian. The 
results are much the same with those obtained by MM. Tingey and Peschier 
from the water of Cachat. In the present case special attention was paid to 
the glairine and the bituminous substance contained in the water of Guillot. 
But one communication has this year been presented on the subject of light, 
and for that the Society is indebted to a young physicist who is not one of its 
members. M. Lucien de la Rive favored us, on the occasion spoken of, with 
an account of a new experiment on parallel difiraction, in which he had studied 
the image of the sun. As he has announced his intention of presenting a second 
memoir on this subject, I shall attempt no analysis of the former, more especi- 
ally as it would involve details which the limits of this report will scarcely per- 
mit. or a like reason, and because it has been already printed in the Biblio- 
theque Universelle, I restrict myself to a single notice of the paper read by M. 
Thury to the Society, entitled, “Remarks on an article of Silliman’s Journal, 
relative to Spencer’s microscopes and the structure of the wood of the conifera ; 
and considerations on microscopes in general.’”” We all remember how many 
important remarks on microscopes, and how many practical instructions, as pre- 
cise as they are useiul, with reference to the present state of those instruments, 
are contained in the paper in question. As to the pores of the conifers, con- 
trary to the figures given by the American author, M. Thury has satistied him- 
self, by direct observation, that the thin membrane which, according to some 
naturalists, forms the base of these pores, really exists, and the organization 
remarked by M. Clarke in the old wood can be only the result of an alteration 
of the organs. 
NATURAL SCIENCES, 
In commencing a review of this branch of the occupations of the Society, 
geological communications are those which first present themselves. Professor 
Favre, having lately visited Amiens in Picardy, gave the results of his exrlo- 
