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was poured into a glass containing it, it expanded into a globule of elastic fluid, of an orange colour, which diminished as it passed through the water.

I attempted to collect the products of the explosion of the new substance, by applying the heat of a spirit lamp to a globule of it, confined in a curved glass tube over water: a little gas was at first extricated, but long before the water had attained the temperature of ebullition, a violent flash of light was perceived, with a sharp report; the tube and glass were broken into small fragments, and I received a severe wound in the transparent cornea of the eye, which has produced a considerable inflammation of the eye, and obliges me to make this communication by an amanuensis. This experiment proves what extreme caution is necessary in operating on this substance, for the quantity I used was scarcely as large as a grain of mustard seed.

A small globule of it thrown into a glass of olive oil, produced a most violent explosion ; and the glass, though strong, was broken into fragments. Similar effects were produced by its action on oil of turpentine and naphtha. When it was thrown into ether there was a very slight action ; gas was disengaged in small quantities, and a substance like wax was formed, which had lost the characteristic properties of the new body. On alcohol it acted slowly, lost its colour, and became a white oily substance, without explosive powers. When a particle of it was touched under water by a particle of phosphorus, a brilliant light was perceived under the water, and permanent gas was disengaged, having the characters of azote.

When quantities larger than a grain of mustard seed were used for the contact with phosphorus, the explosion was always

so violent as to break the vessel in which the experiment was made. The new body, when acted upon under water by mercury, afforded a substance having the appearance of corrosive sublimate, and gas was disengaged. On tin foil and zinc it exerted no action; it had no action on sulphur, nor on resin. In their alcoholic solutions it disappeared as in pure alcohol. It detonated most violently when thrown into a solution of phosphorus in ether, or in alcohol. Phosphorus introduced into ether, into which a globule of the substance had been put immediately before, produced no effect. In muriatic acid it gave off gas rapidly, and disappeared without explosion. On dilute sulphuric acid it exerted no violent action. It immediately disappeared without explosion in Libavius's liquor, to which it imparted a yellow tinge.

It seems probable, from the general tenor of these facts, that the new substance is a compound of azote and chlorine; the same as, or analogous to, that mentioned in the letter from Paris. It is easy to explain its production in our experiments: the hydrogen of the ammonia may be conceived to combine with one portion of the chlorine to form muriatic acid, and the azote to unite with another portion of chlorine to form the new compound. The heat and light produced during its expansion into gaseous matter, supposing it to be composed of azote and chlorine, is without any parallel instance, in our present collection of chemical facts; the decomposition of euchlorine, which has been compared to it, is merely an expansion of matter already gaseous. The heat and light produced by its rarefaction, in consequence of decomposition, depend, probably, on the same cause as that which produces the flash of light in the discharge of the air gun.

The mechanical force of this compound in detonation, seems to be superior to that of any other known, not even excepting the ammoniacal fulminating silver. The velocity of its action appears to be likewise greater.

I am, my dear Sir,

with great respect, very sincerely your's,

H. DAVY.

[8]

II. On a remarkable Application of Cotes’s Theorem. By J. F.W.

Herschel, Esq. Communicated by W. Herschel, LL. D. F.R.S.

Read November 12, 1812.

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LET

ET a represent the semi-transverse axis of a conic section, ae the eccentricity, and consequently a (1 – °)=p the semiparameter. Let also a =

and a=

? = the distance between a point in the curve, and the focus, which, for distinction's sake, we shall call the first focus, and the adjacent vertex the first vertex: the others the second. (2)

= the distance between the same point and the second focus.

R= its distance from the centre.
p=its distance from the first vertex.

0 = the angle contained between the pl"), and the prolongation of a line joining the first vertex and focus.

o= the angle contained between the R and a line joining the first vertex and centre. 4 = the angle contained between the p and the same line. .cot.fo=.cot. Jo=V1. cot. 10.

ita's 0 is the angle whose supplement is, in physical astronomy, known by the name of “ true anomaly," and w is the corresponding “ eccentric anomaly.”

tan. į

I-2'

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Ito

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a.

1-..cos. O; and p(2)

I-E. cos. O

R =

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a.

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p(2) =

The following equations are readily obtained. a (1-2)

- pl1). 1-24 . cos. O te? g(!) = a(1-e.cos. o); p(?) = a(a +e.cos. s)

a' (1-2)

I-e. (cos.P)
za (1-2).cos. -2p. cos.
р P

1-6. (cos. ) I-e. (cos. 4)*

ze=1+27 and 2.e-! = n+1-. Hence wc deduce the following (1-6)(1+1)

{2} 1-27.cos. 0 +12

1-2e . cos. 8+e? = a (1+).

{-} 1 -22. cos. 0 +29 1-2e . cos. 0 + ex

· {3} :a. 122. . cos. a t'na

{4} Ita? I--22. cos. (T – ) + 13

1+12 where a = 4

4{1 - [ + } - * * &c.}. I-22 . cos, a +22

{6} 1-21 . cos. (1-0)+10

a* (I-e") (1 +49) R$ { 1–28. cos. R+no}{" 1–27. cos. (r—p) +10

*}

{7} za (I-e)(1+2)?. cos. 1–22. cos. 4+10}{ (~~) +10}

{8} And lastly, since 1-e.cos. w=

we find cos. A = ell-e-'.cos. a

(2)

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again p(1)

= a.

(1)

(2)

.

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I-e?
I-e, cos. A'

e-e-1

é't

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MDCCCXIII.

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