Chemical Science. 439 
had not become in the least putrid. Neither albumen, traga- 
canth gum, jelly, nor starch, produced with magnesia the same 
effect. Nor does lime or white bole produce the same effect on 
salep. The jelly is insoluble in water, fat oils, oil of turpentine, 
alcohol, or caustic potash, acids partly dissolve it, the remainder 
being bulky and opalescent.—Ana. Phil. iv. 469. 
10. Affinity of Glass for Water.—M. Gay-Lussac mentions 
that the affinity of glass for water is so great, that, after 
being dried, it abstracts from air part of its hygrometric 
water. 
11. On the porosity of Glass and siliceous Bodies. —Mr. Deu- 
char in a paper on the occasional appearance of water in the 
cavities of crystals, and on the porous nature of quartz and 
other crystalline substances, which paper was read before the 
Wernerian Natural History Society, suggests that the crystals 
which are found to contain these portions of water were proba- 
bly once hydrated, or rather, contained throughout their mass 
an excess of water, and that this fluid having afterwards sepa- 
rated from the crystals passed by capillary attraction either to 
the surface, or to any accidental void space within them. 
Mr. Deuchar thinks it obvious that the water might pass 
through the crystals, not only from the porous nature of their 
particles, but also from their temporary display of rents during 
the application of a high temperature. It is supposed that all 
siliceous bodies, even glass, §c., are porous, and the author 
thinks that the filling of well-stopped bottles, when sunk to 
great depths in the ocean, depends on the water passing through 
the glass, and not through the materials used to stop the bottles, 
though these were only cork, sealing-wax, and oil-cloth. We 
would, however, refer our readers to the paper itself in the 
Phil. Mag. \x. 310., but wish them at the same time to read one 
by Mr. Scoresby, in the Edin. Journal, vi. 115., also relating 
to sunken bottles. 
12. On the Temperature produced by Vapour, and on the 
Temperature of Vapour, by M. Faraday, Chem. Assistant, §c.— 
I had occasion to observe, a short time since, a curious property 
of vapour, which, though it appears to have been known to 
some philosophers, had not been generally noticed, and had 
never, I believe, been published. It is the power it possesses 
of raising certain bodies to a temperature higher than its own. 
The fact may easily be observed, by holding a thermometer 
horizontally in a current of steam as it issues from the mouth 
of a tea-kettle or a flask, or any other vessel; and when it has 
attained 212°, dropping a little powdered tartrate of potash 
or muriate of ammonia or nitre on to it; the temperature will im- 
