Natural-Philosophical- Collections. 389) 
or the deutoxide of arsenic, also furnishes ammonia in its decomposition, which 
always takes place with detonation. ; 
' 4. The fulminating silver of Berthollet, regarded as an ammoniuret or an azo-: 
turet, presents the same results; it gives ammonia, of whose reproduction. there. 
ean be no doubt, seeing that, in certain circumstances, there is a disengagement 
of nitrogen without a reaction capable of decomposing the aminonia ; it is, ac- 
cording to M. Serullas, an azoturet of silver. 
5. On introducing some per-chloruret of phosphorus into a flask full of dry sul- 
phuretted hydrogen, hydro-chloric acid gas is disengaged, with ebullition, and. 
a transparent colourless liquid is shortly formed, which M. Serullas considers to 
be composed of phosphorus, chlorine, and sulphur, in definite proportions. — 
Universel, Aug. 1829. 
The same eect ue has recently communicated to the Academy of Sciences 
a memoir, entitled, ‘‘ on the action of different acids on the neutral iodate of po- 
tassa ;—acid iodates of this base, or bi-iodate and tri-iodate of potassa ;—chloro- 
iodate of potassa;—new mode of obtaining iodic acid :”’ from which we gather 
the following results : 
1. There exist two iodates of potassa. 
‘The first is produced by the incomplete saturation of chloruret of iodine with 
potassa, under the form of a double crystalline compound, which, on being sepa- 
rated, dissolved and crystallized, gives the bi-iodate. 
The other results from the action of one of the following acids, sulphuric, ni- 
tric, phosphoric, hydro-chloric, and fluo-silicic acid, on the neutral iodate of po- 
tassa; or it may be better obtained by treacing dircedly, a great excess of iodic 
acid orc potassa. 
2. In the incomplete saturation of chloruret of iodine with potassa, a double 
compound is formed, in definite proportions, of the chloruret of SUES SET and of 
the acid iodate of potassa. 
3. There exists no acid iodate, nor chloro-iodate of soda. 
4. One may, with great advantage, substitute for the process of Davy, to ob- 
tain iodic acid by the oxide of chlorine and iodine, that of precipitating the soda 
from the iodate of this base, by means of fluo-silicic acid. 
~ On the Undulatory Fheory of Light.—M. Ampere laid before the Academy, 
some time since, two memoirs, relative to important questions respecting the 
theory of light, which he has since published, under the following title: Memoir 
on the curved surface of the waves of light, in a medium whose elasticity is dif- 
JSerent according to the three principal directions, in other words, that in which 
the force produced by elasticity takes place in the direction of the displacement 
of the molecules of this medium. ‘These questions originated in the researches 
of a member of the Academy, whom a premature death snatched from the sciences 
before he had accomplished his undertaking. 
In his first memoir, M. Ampere directly determines the surface of the lumi- 
nous wave in crystals, in which the velocity of light is diterent according to the 
three straight lines at right angles to each other, which have_been called the 
Three Axes of the Surface of Elasticity. By proceeding from the common equa- 
tion to all the tangent points, M. Fresnel had deduced that of the surface of the 
Inminous wave, on the supposition that this equation does not pass the fourth 
degree. 
M. Ampere’s second memoir contains the demonstration of a theorem, which 
M. Fresnel had only announced, conning himself to showing that this theorem 
leads to the equation which he had given for the luminous wave. M. Ampere 
‘takes quite-a different method ; he deduces M. Fresnel’s theorem from the pre- 
ceding equation, which he demonstrated directly in his first memoir. The theo- 
_rem in question ought to be considered as the most simple enunciation of the 
laws of the propagation of light in crystallized media. These laws being con- 
firmed by observation, are, propery spe aking, data of experiment. There re- 
sults from them a means of comparing and appreciating the various hypotheses 
