N I T

NIT

( 1 52 )

takes the excefs of oxygen from the oxymuria-tic, and vaporized nitrous acid fucceeds, but iffufficient water be prefent, this acid vapour,together with the muriatic gas feparated fromthe oxymuriatic, is abforbed by the water, andliquid nitro-muriatic acid is produced.

Dr. Prieitley' has found that a very powerfulaqua regia which diffolves gold with greatrapidity may be formed by impregnating liquidmuriatic acid with the nitrous acid vapour(defcribed in the lad article). The proportionof condiment parts here widely differs from thofeof the common aqua regia for gold, which ladis ufually made by three fourths of nitric andone fourth of muriatic acid; whereas in makingthe other acid the liquid muriatic acid hardlyincreafes in bulk by faturation with the nitrousvapour. Dr. P. alfo tried to form a nitro-muriatic acid that would diffolve gold by im-pregnating nitrous acid with muriatic acid gas,hut without fuccefs, as the liquor would nottouch this metal. As foon as the muriatic acidreceives the nitrous vapour it changes from apale draw to a deep orange, much deeper thannitrous acid alone can be brought to.

When nitro-muriatic acid is faturated withan alkali the nitrous gas which it had abforbedis given out, and the liquor duly evaporatedgives both a nitrat and muriat of the alkali ufed.But when the acid is faturated with a metal therefulting fait is ufually a fimple muriat, thenitric acid having been employed to oxygenatethe metal and thus to render it (in mod indan-ces) foluble in the muriatic acid, to which modmetallic oxvds have the ftronged affinity.

'NITRAT OF POTASH. Nitre. Salt-petre.

Nitre is a neutral fait compofed of nitric acidand potadi in a date of perfeft mutual faturation.Its primitive crydalline form is that of a re&an-gular octohedron, compofed of two pyramidsapplied bale to bafe, in fuch a manner that twooppofite fides of the upper pyramid form withthe correfponding fides of the lower one anglesof i 20°, while the two other oppofite fides formwith their correfponding ones angles of ni°.This figure however is of very rare occurrence.When the lummits of the pyramids are deeply^truncated, the refult is a bevilled reCtangular table, which is by no means unfrequent. But.the mod ufual form which this fait affumes is.that of the common quartz cry dal, viz. a draitfix-fided prifm terminated at each extremity by.a fix-fided pyramid. The fpecific gravity ofLiitre according to Newton, is = 1.9, according

>* Obs. pn Air, voliii. p. 14.6. * Ann. Ch. xxYiii. p. l£.

to Mufchenbroek, = 1,901, and according toHaflenfratz, = 1.9369: b the latter of thefeedimates feems to be the lead correct. It hasa ffiarp faline and cooling though difagreeabletade. When fully cryftallized it is very brittle,and the larger priimatic crydals if held in thewarm hand, will crack acrofs with a veryaudible noife. It generally attracts a little moif-ture on expofure to the air, but this is probablyto be attributed to the cafual mixture of a ffnallportion of deliquefcent fait. With regard tothe degree of folubility of nitre in water ofdifferent temperatures, there exid fome contra-dictions that require to be cleared up : accord-ing to Bergman, this fait is foluble in feventimes its weight of water at the ufual tempera-ture, and in about its own weight of boilingwater; from the experiments of Haflenfratzhowever it appears that a hot faturated folutionof nitre, after being cooled down to 6i° Fahr.and remaining at this temperature 24 hours,holds nearly ( of its weight of fait, and at 54 0Fahr. about j- of its weight: according toBeaume, c 4 ounces of boiling water will takeup 10 ounces of nitre when the folution ismade in a matrafs, but if a bafon or any otheropen veflel is made ufe of, a pellicle begins toform at the furface of the liquor when it con-tains water and fait in equal proportions. Thefollowing table of the fpecific gravity and com-pofition of folutions of nitre in water at 6i°Fahr. has been condructed by Haflenfratz. d

Sp. gr. of folution Proportion of Nitre in

at 6i° Fahr. 100 parts of folution.

1.006

- - -

-

-

I

1.012

- - -

-

-

2

I.0l8

- - -

-

-

3

I.024

- - -

“

4

1.03°

- " "

-

5

i -°35

- - -

-

-

6

1.040

- - -

-

-

7

1.046

- - -

-

-

8

T °53

' - -

-

9

1.059

- - -

-

-

10

1.065

- " *

-

11

1.072

- * -

-

12

1.078

- - -

-

“

J 3

1.085

- - *

-

-

14

1.091

- " “

-

15

1.098

- - '

-

-

16

1.105

- - *

-

-

17

1.111

- - -

*

_

18

1.118

- - -

19

1.125

“ “ -

-

-

20

* Chem. expcr. i.

p. 414. * Ann. Ch.

xxvii. p.