EXPERIMENTS.

NOTHING tends to imprint chemical facts upon the mind so much as the exhibition of interesting Experiments. this view the following Selection has been made, in which such experiments as may be performed with ease and safety, have uniformly been preferred.

No. 1. Take a small phial about half full of cold water; grasp it gently in the left hand, and from another phial pour a little sulphuric acid very gradually into the water. A strong SENSATION OF HEAT will immediately be perceived. This, by the continued addition of the acid, may be increased to many degrees beyond that of boiling water. See pages 73 and 84.

2. Take a small phial, in one hand, containing some pulyerized muriate of ammonia; pour a little water upon it, and shake the mixture. In this instance a SENSATION OF COLD will immediately be felt. See page 76.

3. Into a tea-cup, placed upon a hearth, and containing about a table spoonful of oil of turpentine, pour about half the quantity of strong nitrous acid, previously mixed with a few drops of sulphuric acid. The moment the acids come in contact with the turpentine, FLAME will be produced. In performing this experiment it is advisable to mix the acids in a phial, to tie the phial to the end of a stick, and, at arm's length,

to pour its contents into the oil; as the sudden combustion sometimes occasions a part of the liquids to be thrown out of the vessel See note, page 74.

4. Put about an ounce of marble grossly pulverized into an eight-ounce phial, with about an equal quantity of water. Pour upon it a little sulphuric acid, and CARBONIC ACID GAS will be evolved. See page 284.

5. Put about an ounce of iron filings into a phial with about three or four ounces of water; pour a little sulphuric acid upon the contents, and HYDROGEN GAS will be evolved. See notes, page 104.

6. Pour water into a small glass retort so as to occupy about one third of its capacity, lute its beak into the end of a gun barrel, the middle of which must be kept red-hot in a furnace, or by a chaffing dish; then if a lamp be applied to the retort so as to cause the water to boil, the steam will pass through the red-hot iron tube, and in this case also will be decomposed; for, as the oxygen combines with the iron, the HYDROGEN GAS will be liberated, and may be collected in the usual way. See page 101.

7. Put some sulphuret of iron into a phial, pour a little diluted sulphuric acid over it, aud attach a bladder, prepared as directed for experiment No. 4. to the phial. SULPHURETTED HYDROGEN, a gas extremely fetid and disagreeable, will immediately be evolved; though the ingredients here employed were destitute of smell. See page 253.

nce or two of the black oxide of manganese retort, pour a little concentrated sulphuric pply the heat of a lamp. OXYGEN GAS in abundance. See Additional Notes, No. 7.

9. Into a small glass retort put a mixture of two parts of quick-lime, and one of muriate of ammonia, both in powder. Apply the heat of a lamp, and AMMONIACAL GAS will come over. See page 164.

The cheapest receiver for the collection of this and other gases is a moistened bladder, with a piece of tobacco-pipe firmly tied into its neck, and twisted in such a manner as to expel all the common air. This may easily be adapted to any vessel by means of the pipe, which may be fixed in the cork, and closely luted in the usual way.

10. Pour a little sulphuric acid upon a small quantity of quicksilver in a glass retort, apply heat, and SULPHURÓUS. ACID GAS may be collected. See page 178.

11. Take a few shreds or filings of copper, and pour over them a little diluted nitrous acid, in the proportion of about three parts of water to one of acid. The gas evolved in this case is NITROUS GAS. See page 185.

12. Upon an ounce or two of nitrate of potass in a glass retort pour some sulphuric acid; give it heat by means of a lamp, and collect NITROUS ACID. See page 184.

13. Treat muriate of soda in the same manner with sulphurie acid, and MURIATIC ACID in the gaseous form will rise from the retort. See note, page 180.

14. Convey some muriatic acid gas into a glass jar containing a portion of the gas produced in experiment 9. From the mixture of these two invisible gases a SOLID SUBSTANCE will be produced, viz. the common sal ammoniac; this may be perceived to deposit itself upon the sides of the vessel in a neat crystallized form. See pages 165 and 166.

15. Convey some carbonic acid gas into a glass jar containing a portion of ammoniacal gas. The instant the two gases come into contact a great absorption will take place, and SOLID CARBONATE OF AMMONIA will be formed on the inner surface of the jar. See page 164.

16. If common Glauber's salt be dried and reduced to powder, as directed note, b, page 237, and then dissolved in three times its weight of boiling water, it will not only be found to crystallize again on cooling, but the crystals will assume the identical forms which they exhibited before they were pulverized. This experiment is designed to show that a DETERMINATE FIGURE has been instamped upon every INDIVI

DUAL SALT.

17. Dissolve of an ounce of Glauber's salt in two ounces of boiling water, pour it while hot into a phial and cork it close. In this state it will not crystallize, even when perfectly cold; but if the cork be now removed, the crystallization will be seen to commence and proceed with rapidity; affording an instance of the effect of ATMOSPHERIC AIR on CRYSTALLIZATION. See page 234.

18. Repeat the experiment with a small thermometer immersed in the solution, and closed so as to exclude the atmospheric air. If the solution be suffered to cool completely under

these circumstances, the thermometer will be seen to rise on the removal of the cork. This experiment is designed to show that saline solutions give out CALORIC in the act of CRYSTALLIZATION. See note, page 76.

19. Put about half an ounce of quicksilver into a wine-glass, and pour about an ounce of diluted nitrous acid upon it. The nitrous acid will be decomposed by the metal with astonishing rapidity; the bulk of the acid will be quickly changed to a beautiful green, while its surface exhibits a dark crimson: and an effervescence indescribably vivid and pleasing will go on. during the whole time the acid operates upon the quicksilver. When a part only of the metal is dissolved, a change of colour will again take place, and the acid by degrees will become paler, till it is as pellucid as pure water. This is one instance of a METALLIC SOLUTION by means of an ACID; in which the opacity of a metallic body is completely overcome, and the whole rendered perfectly transparent.

20. Take the metallic solution formed in the last experiment, add a little more quicksilver to saturate the acid; then place it at some distance, over the flame of a lamp, so as gently to evaporate a part of the water. The new formed salt will soon be seen to begin to shoot into needle like prismatic crystals, crossing each other in every possible direction; affording an instance of the FORMATION of a METALLIC SALT.

21. Pour a drachm by weight of strong nitrous acid into a wine glass, add two drachms of distilled water *, and, when mixed, throw a few very small pieces of granulated tin into it. A violent effervescence will take place, the lighter particles of the tin will be thrown to the top of the acid, and be seen to play up and down in the liquor for a considerable time, till the whole is dissolved. This is another example of a TRANSPARENT LIQUID holding a METAL İN SOLUTION.

22. Dissolve one ounce of quicksilver without heat in of an ounce of strong nitrous acid, previously diluted with one ounce and a half of water. Dissolve also the same weight of quicksilver, by means of heat, in the same quantity of a similar acid, and then to each of these colourless solutions add a colourless solution of ammonia. In the one case, the metal will be precipitated in a black, in the other, in a white powder, affording an ex

*Where distilled water is not at hand, clean rain water will answer nearly as well for most purposes.