water, if you wish to make solution of h. sulphide, or the solution to be treated with the gas. During the passage of the gas keep shaking C, as this considerably facilitates absorption. When it is imagined that the fluid in C is saturated with the gas, take out the cork, cover the mouth with your hand, and shake; if the hand is not drawn in, the liquid is saturated.

In this way the unabsorbed hydric sulphide. continually escapes into the air, and the experiment should be done in a draught cupboard; or, if in the country, in the open air. It is better also to burn the escaping excess of gas by passing it through a gas flame, and thus convert it into the less offensive sulphurous acid. Get a two-inch brass tube of the same diameter as the barrel of the Bunsen, in the side of which is soldered another shorter tube; fix the long tube upright on the top of the Bunsen by india-rubber, and attach the short tube by india-rubber to the exit of C.

When the operation is finished, take the cork out of the generating bottle, apply a light, and immediately fill it with water, then empty the liquid. If any lumps remain, wash them, and keep them in the bottle for future use.

The solution of h. sulphide soon loses all its strength in contact with the air. If the bottle is full, well closed and inverted, the solution will keep for months.

Hydrosodic phosphate (Na,HPO,).

Boil 50 c.c.

water, add 4 grm. of the salt, and when solution is effected add 50 c.c. water.

Mercuric chloride (HgCl). Boil 50 c.c. water, add

4 grm. of the salt in powder, and when solution is effected add 50 c.c. water.

Platinic chloride (PtC1). Put 2 grm. platinum foil clippings in a flask, add h. chloride conc. and about one-third its volume of h. nitrate conc., warm gently till dissolved. If after some time the action seems to have ceased and platinum still remains undissolved, pour off the liquor, add fresh acids, and continue the digestion. Transfer the solution to a dish, evaporate on a water bath to the consistence of syrup, and add 100 c.c. water. Potassic nitrite (KNO).

Support a stoppered retort with the neck slanting a little upwards. Into the neck fit a tube so bent as to have a long limb perpendicularly downwards. In the retort put h. nitrate conc. and lumps of arsenious acid. Let the tube dip into 200 c.c. water in which 50 grm. potash (KHO) have been dissolved. Warm the retort by the aid of a water bath, and pass the evolved nitrous acid into the potash till no more is absorbed. Soda (NaHO). To 50 grm. caustic soda broken small add 250 c.c. boiling water, and when a solution is obtained add 250 c.c. more water. Allow to settle, and draw off the clear liquor.

Stannous chloride (SnCl). Mix 50 c.c. h. chloride conc. with 50 c.c. water, boil and add 10 grm. of the salt.

ANALYSIS OF SINGLE SUBSTANCES (OXIDES AND SALTS).

If a sublimate not S, mix substance with dry Na,CO, and heat in ignition tube before blowpipe.

2. Mix substance with Na,CO, and KCy and heat on charcoal in inner blowpipe flame.

RESULTS.

A sublimate of S
A sublimate not S
Smell of NH,
Globules of Hg
Mirror of As

Metallic globules, malleable
brittle

Garlic odor

3. If the substance is colored, heat in borax bead in The cold bead isouter blowpipe flame.

blue

blue

green

brown, yellow or bottle green amethyst red

yellowish green

Cu.BO3
Ba

crimson

red

yellow violet

No action in any of above experiments. Zn. Al.Mg

4. Heat substance on platinum wire before the blow- The flame is coloredpipe.

green

5.

Practice in Table A.

(The object of this examination is by a few simple blowpipe experiments to get a fair idea of the metal present, and also to show how a metal may be tested for in the dry way.)

1. Take some ignition tubes (p. 32) and put into one a minute quantity (about as big as two or three pins' heads) of the substance, hold the end. of the tube in a Bunsen flame, and if no action takes place apply the blowpipe flame. The following substances will give definite results :—

FeS, CuFeS, decompose and give a sublimate of S.

HgCl, HgCl,, AmCl, As,О ̧, As,S„, HgI, HgS sublime without decomposition.

HgO decomposes and gives a sublimate of Hg. (Many other substances are decomposed, such as FeSO, ZnSO, Alum, KCIO,, and nitrates.)

Among these results sublimates are most striking; one of S is recognisable immediately; one not S will probably be produced by Am, Hg or As. Compounds of these metals may be distinguished at once by the following experiment :

Mix a pin's head of the powdered substance with 10 or 20 times its quantity of perfectly dry Na,CO, on a piece of paper by means of a penknife, put the mixture into an ignition tube, and apply the blowpipe flame. (If the Na,CO, is not perfectly dry the water will make a mess in the ignition tube.)

The following substances may be used :—

AmCl gives a smell of NH..

HgCl gives globules of Hg.

As,0, gives a mirror of As, which is black or steely according to the quantity.

2. Take a piece of fine charcoal nearly free from fissures, cut it lengthwise in half with a saw, and scoop a cavity in the flat surface. Now mix a little KCy+ Na,CO, on paper with a little of the substance in powder, put the mixture in the cavity, and apply a blowpipe flame.

If metallic globules are formed, allow the charcoal to cool, take out a large globule with the point of a penknife, put it in a mortar, and hit it with the pestle to see if it is brittle or malleable. If the globules are very small they may be separated from the flux and charcoal by scooping the whole mass out, grinding it in a mortar with water, and washing away all soluble and light particles under the tap. If any particles of metal are present they will remain and shine at the bottom, and it will be evident whether they are malleable or brittle. If fumes are noticed, take the charcoal quickly to your nose.

The following substances may be used:

Oxides or salts of Pb,Ag,Sn give malleable globules.

Sb,Bi

brittle

Compounds containing As give a garlic odor.

Some oxides and salts are reduced to metal by heating on charcoal alone, while many more require a flux of Na,CO,. The addition of KCy, however, which is the most powerful dry reducing agent, assists the action of the Na,CO,.

3. Take a piece of platinum wire three or four inches long, and make a loop at one end (the