236 
‘globe, without producing a change in the 
distribution of this generally prevading 
principle, which Mr. P. has not attempted 
to designate by any particular name. If a 
gas become a fluid, or a fluid a solid, there 
is a diminution of capacity for heat ; there 
is a contraction of yolume, and the form 
this matter has now assumed, owing to 
contraction, demands less of this generally- 
pervading principle, and heat is in con- 
sequence presented to surrounding bodies. 
If this change take place with rapidity, and 
bodies possessing a great capacity for heat, 
as water or moisture, be absent, light will 
frequently result: hence the electric spark. 
While, on the contrary, if a solid be- 
come a fluid, or a fluid a gas, there is an 
increase of capacity, there is expansion of 
yolume, and the form now assumed will, 
owing to this extension, demand more of 
this all-pervading principle, and cold will in 
consequence be presented to, or their per- 
vading heat be abstracted from surrounding 
bodies. Moreover, if a gas merely contract 
or expand, without assuming either the 
fluid or solid form, the same effect will be 
produced upon the pervading principle of 
heat in surrounding bodies. Electric or 
galvanic action between bodies is the re- 
sult of their containing different proportions 
of the all-pervading principle ; and by the 
electric spark the excess is given off, and 
an equilibrium restored. So the thunder 
cloud, being formed of vapour in the at- 
mosphere, having suffered a contraction of 
volume, has an excess of the pervading 
principle, which, by being transmitted to 
the earth beneath, or to another cloud 
which has suffered expansion, produces 
lightning. 
Conducting power appears to Mr. P. to 
be the consequence of the strong mutual 
attraction existing between the particles of 
matter, as ina metal; it appears to depend 
upon the particles bemg nearer to each 
other than in bodies which have consider- 
able capacity for heat, where the attraction 
is less strong, and the particles further 
separated. Thus the metals are found to 
possess the least capacity for heat of all the 
forms of matter: in water, these two 
powers are mere equally blended than in 
any other body ; it possesses a greater con- 
ducting power than any other fluid of equal 
density, and has a greater capacity for heat. 
It exists in three forms, solid, fluid, and 
gaseous, at a jess variation of tempe- 
rature than any others of, the fluid com- 
pounds ; and by the aetion. of heat alone, 
differs from all others in. being unalterable 
in composition. . Mr, P.’s mode of applying 
these principles to account for Voltaic ac- 
tion not admitting of an intelligible abridg- 
ment, we must refer for it to the journal 
quoted. 
Jodous Acid has lately been added by 
Signor Sementini to the number of the 
known combinations of iodine with oxigen ; 
and he has stated the following as its dis- 
Spirit of Philosophical Discovery. 
[Oct. 1, 
tinguishing differences from the iodic acid 
which was before known: iodic acid is 
solid, white, without odour, reddening blue 
colours, and then destroying them ; is vo- 
latile at 456° Farenh. with decomposition ; 
and heated with charcoal or sulphur, it is 
decomposed with detonation. | Whereas 
iodous acid is liquid, yellow, odorous, red- 
dening blue colours, but not destroying 
them : volatilizes at 112°Farenh., and even 
at common temperatures, without decom- 
position: heated with sulphur it is decom- 
posed without detonation, and inflames po- 
tassium and phosphorus by mere contact. 
—Biblo. Univ., vol. xxv, p. 119. 
The sweet-scented Violet is a poisonous 
plant. Messrs. Boullay and Orfila have 
ascertained that the violet (viola odorata) 
contains an active alkaline, bitter, and acrid 
principle, which they denominate violine, 
which greatly resembles the emetine of 
ipecacuanha : it is found to reside equally 
in the roots, leaves, flowers, and seeds of 
the plant, and to possess powerful poison- 
ous qualities. 
Cyanic acid, in combination with a metal, 
is found to compose the various fulminating 
powders. —Messrs. Liebeg and Gay Lussac, 
in experimenting on various fulminating 
mixtures, have ascertained that many, and 
probably all of them, owe this explosive 
property to cyanogen and oxigen entering 
into their composition. They found, for 
instance, fulminating silver composed as 
follows, viz. 
Silver. ..... 72-19 
Cyanogen .. 17-16 
Oxigen .... 10-65 
100-00 
Ann. de Chim., vol. xxv. p.-285. 
Sulphurous acid gas has been liquefied by 
M. Bussy, producing a colourless, trans- 
parent, and very volatile liquid, of a specific 
gravity 1-45; it boils at 14° of Farenh., 
but produces so much cold )in evaporating, 
as to occasion, for some time, a portion of 
the acid to remain liquid. When the at- 
mosphere was at 50°, the bulb of a ther- 
mometer, wrapped in cotton, dipped into 
this liquid acid, occasioned the mercury to 
fall almost instantly to—70° of Farenh., as 
measured by an air thermometer. | In the 
vacuum of the air-pump, a cold of—90° 
Farenh. was produced by its evaporation ! 
by which, not only was mercury) readily 
frozen, but also.alcohol (of a spec. grav. 
below -852, at 55° of Farenh. ) was completely 
frozen ! Tubes cooled by the evaporation 
of this liquefied acid .readily occasioned 
the liquefaction of chlorine, and of ammonia, 
when passed through them : and cyanogen, 
under the same treatment, was obtained in 
a solid crystalized form.—dAnn. de Chim. 
Cafeine, a new principle in coffee.— Messrs. 
Robiquinet, Pelleter, and: Caventor, in ex- 
perimenting upon coffee-berries, have dis- 
covered and separated a new chemical sub- 
stance—white, crystalline, volatile, and 
slightly 
