We have already pointed out the possibility of going through a course of physics without any special apparatus, we shall now endeavour to show our readers the method of performing some experiments in chemistry without a laboratory, or at any rate with only a few simple and inexpensive appliances. The preparation of gases, such as hydrogen, carbonic acid, and oxygen, is very easily accomplished, but we shall here point out principally a series of experiments that are not so much known. We will commence, for example, by describing an interesting experiment which often occurs in a course of chemistry. Ammoniacal gas combined with the elements of water is analogous to a metallic oxide which includes a metallic root, ammonium. This hypothetically composed metal may be in a manner perceived, since it is possible to amalgamate it with mercury by operating in the following manner:—We take a porcelain mortar, in which we pour a quantity of mercury, and then cut some thin strips of sodium, which are thrown into the mercury. By stirring it about with the pestle a loud cracking is produced, accompanied by a flame, which bears evidence to the union of the mercury and the sodium, and the formation of an amalgam of sodium. If this amalgam of sodium is put into a slender glass tube containing a concentrated solution of hydrochlorate of ammonia in water, we see the ammonia expand in an extraordinary manner, and spout out from the end of the tube, which is now too small to contain it, in the form of a metallic substance (fig. 302). In this case, the ammonium, the radical which exists in the ammoniacal salts, becomes amalgamated with the mercury, driving out the sodium with which it had previously been combined; the ammonium thus united with the mercury becomes decomposed in ammoniacal gas and hydrogen, the mercury assuming its ordinary form. Phosphate of ammonia is very valuable from its property of rendering the lightest materials, such as gauze or muslin, incombustible. Dip a piece of muslin in a solution of phosphate of ammonia, and dry it in contact with the air; that done, you will find it is impossible to set fire to the material; it will get charred, but you cannot make it burn. It is to be wished that this useful precaution were oftener taken in the matter of ball-dresses, which have so frequently been the cause of serious accidents. There is no danger whatever with a dress that Fig. 302.—Experiment with ammonium. For preparing cool drinks in the summer ammoniacal salts are very useful; some nitrate of ammonia mixed with its weight in water, produces a considerable lowering of the temperature, and is very useful for making ice. Volatile alkali, which is so useful an application for stings from insects, is a solution of ammoniacal gas in water, and sal-volatile, which has such a refreshing and reanimating odour, is a carbonate of ammonia. We often see in chemists’ shops large glass jars, the insides of which are covered with beautiful transparent white crystals, which are formed over a red powder placed at the bottom of the vase. These crystals are the result of a combination of cyanogen and iodine. Nothing is easier than the preparation of iodide of cyanogen, a very volatile body, which possesses a strong tendency to assume a definite crystalline form. We pound in a mortar a mixture of 50 grams of cyanide of mercury, and 100 grams of iodine; under the action of the pestle the powder, which was at first a brownish colour, assumes a shade of bright vermilion red. The cyanogen combines with the iodine, and transforms itself into fumes with great rapidity. If the powder is placed at the bottom of a stoppered glass jar, the fumes of the iodide of cyanogen immediately condense, thereby producing beautiful crystals which often attain considerable size (fig. 303). Cyanogen forms with sulphur a remarkable substance, sulpho-cyanogen, the properties of which we cannot describe without exceeding the limits of our present treatise; we shall therefore confine ourselves to pointing out one of its combinations, which is well known at the present day, owing to its singular properties. This is sulpho-cyanide of mercury, with which small combustible cones are made, generally Fig. 303.—Iodide of cyanogen. Fig. 304.—Pharaoh’s serpent. After these few preliminary experiments, we will endeavour to show the interest afforded by the study of chemistry in relation to the commonest substances of every-day life. We will first consider the nature of a few pinches of salt. We know that kitchen salt, or sea salt, is white or greyish, according to its degree of purity; that it has a peculiar flavour, is soluble Fig. 305.—Combustion of sodium in water. This remarkable experiment is very easy to carry out, and sodium is now easily procured at any shop where chemicals are sold. The combustion of sodium in water can be explained in a very simple manner. Water, as we know, is composed of hydrogen and oxygen. Sodium, by reason of its great affinity for the latter gas, combines with it, and forms a very soluble oxide; the hydrogen is released and thrown off, as we shall perceive by placing a lighted match in the jar, when the combustible gas ignites. Oxide of sodium has a great affinity for water; it combines with it, and absorbs it in great quantities. It is a solid, white substance, which burns and cauterizes the skin; it is also alkaline, and brings back the blue colour to litmus paper that has been reddened by acids. Sodium combines easily also with chlorine. If plunged into a jar containing this gas it is transformed into a substance, which is sea salt. If the chlorine is in excess a part of the gas remains free, for simple substances do not mingle in undetermined ratios; they combine, on the contrary, in very definite proportions, and 35·5 gr. of dry chlorine always unites with the same quantity of soda equal to 23 grams. A gram of kitchen salt is formed, therefore, of 0·606 gr. of chlorine, and 0·394 gr. of sodium. Besides sea salt, there are a number of different salts which may be made the object of curious experiments. We know that caustic soda, or oxide of sodium, is an alkaline product possessing very powerful properties; it burns the skin, and destroys organic substances. Sulphuric acid is endowed with no less powerful properties; if a little is dropped on the hand it produces great pain and a sense of burning; a piece of wood plunged into this acid is almost immediately carbonized. If we mix forty-nine grams of sulphuric acid and thirty-one grams of caustic soda a very intense reaction is produced, accompanied by a considerable elevation of temperature; after it has cooled we have a substance which can be handled with impunity; the acid and alkali have combined, and their properties have been reciprocally destroyed. They have now originated a salt which is sulphate of soda. This substance exercises no influence on litmus paper, and resembles in no way the substances from which it originated. There are an infinite number of salts which result in like manner from the combination of an acid with an alkali or base. Some, such as sulphate Fig. 306.—Preparation of a solution saturated with sulphate of soda. Sulphate of soda is very soluble in water, and at a temperature of thirty-three (Centigr.) water can dissolve it in the greatest degree. If we pour a layer of oil on a solution saturated with Glauber’s salts, and let it stand, it will not produce crystals; but if we thrust a glass rod through the oil into contact with the solution, crystallization will be instantaneous. This singular phenomenon becomes even more striking when we put the warm concentrated solution into a slender glass tube, A B, which we close after having driven out the air by the bubbling of the liquid (fig. 306). When the tube has been closed, the crystals of sulphate of soda will not form, even with the temperature at zero; nevertheless the salts, being less soluble cold than hot, are found in the fluid in a proportion ten times larger than they would contain under ordinary conditions. If the end of the tube be broken the salt will crystallize immediately. We will describe another experiment, but little known and very remarkable, which exhibits in a striking manner the process of instantaneous crystallizations. Let one hundred and fifty parts of hyposulphite of soda be dissolved in fifteen parts of water, and the solution slowly poured into a test-glass, previously warmed by means of boiling water, until the vessel is about half-full. One hundred parts of acetate of soda is then dissolved in fifteen parts of water, and poured slowly into the first solution, so that they form two layers perfectly distinct from each other. The two solutions are then covered with a little boiling water, which, however is not represented in our illustration. After it has been left to stand Fig. 307.—Experiment of instantaneous crystallization. Another remarkable instantaneous crystallization is that of alum. If we leave standing a solution of this salt it gradually cools, at the same time becoming limpid and clear. When it is perfectly cold, if we plunge into it a small octahedral crystal of alum suspended from a thread, we perceive that crystallization instantly commences on the surface of the small crystal; it rapidly and perceptibly increases in size, until it nearly fills the whole jar. Common Metals and Precious Metals. How many invalids have swallowed magnesia without suspecting that this powder contains a metal nearly as white as silver, and is malleable, and capable of burning with so intense a light that it rivals even the electric light in brilliancy! If any of our readers desire to prepare magnesium themselves it can be done in the following manner:—Some white magnesia must be obtained from the chemist, and after having been calcined, must be submitted to the influence of hydrochloric acid and hydrochlorate of ammonia. A clear solution will thus be obtained, which by means of evaporation under the influence of heat, furnishes a double chloride, hydrated and crystallised. This chloride, if heated to redness in an earthenware crucible, leaves as a residue a nacreous product, composed of micaceous, white scales, chloride of anhydrous magnesium. Fig. 308.—Group of alum crystals. If six hundred grams of this chloride of magnesium are mixed with one hundred grams of chloride of sodium, or kitchen salt, and the same quantity of fluoride of calcium and metallic sodium in small fragments, and the mixture is put into an earthenware crucible made red-hot, and heated for a quarter of an hour under a closed lid, we shall find on pouring out the fluid on to a handful of earth, that we have obtained instead of scoria, forty-five grams of metallic magnesium. The metal thus obtained is impure, and to remove all foreign substances it must be heated in a charcoal tube, through which passes a current of hydrogen. Magnesium is now produced in great abundance, and is very inexpensive. It is a metal endowed with a great affinity for oxygen, and it is only necessary to thrust it into the flame of a candle to produce combustion; it burns with a brightness that the eye can scarcely tolerate, and is transformed Fig. 309.—Calcined alum. The humble earth of the fields—the clay which is used in our potteries, also contains aluminium, that brilliant metal which is as malleable as silver, and unspoilable as gold. When clay is submitted to the influence of sulphuric acid and chloride of potassium, we obtain alum, which is a sulphate of alumina and potash. Alum is a colourless salt, which crystallizes on the surface of water in beautiful octahedrons of striking regularity. Fig. 308 represents a group of alum crystals. This salt is much used in the colouring of fabrics; it is also used for the sizing of papers, and the clarification of tallow. Doctors also use it as an astringent and caustic substance. When alum is submitted to the action of heat in an earthenware crucible, it loses the water of crystallization which it contains, and expands in a singular manner, overflowing from the jar in which it is calcined (fig. 309). Fig. 310.—Preparation of metallic iron. Iron, the most important of common metals, rapidly unites with oxygen, and, as we know, when a piece of this metal is exposed to the influence of damp air, it becomes covered with a reddish substance. In the well-known experiment of the formation of rust, the iron gradually oxidises without its temperature rising, but this combination of iron with oxygen is effected much more rapidly under the influence of heat. If, for example, we redden at the fire a nail attached to a wire, and give it a movement of rotation as of a sling, we see flashing out from the metal a thousand bright sparks due to the combination of iron with oxygen, and the formation of an oxide. Particles of iron burn spontaneously in contact with air, and this property for many Fig. 311.—Pyrophoric iron. Fig. 313 represents cylindrical bars of the best known metals, all weighing the same, showing their comparative density. Fig. 312.—Iron and nitric acid. Lead, like tin, is capable of taking a beautiful crystalline form when placed in solution by a metal that is less oxydisable. The crystallization of lead, represented in fig. 314, is designated by the name of the Tree of Saturn. This is how the experiment is produced: Thirty grams of acetate of lead are dissolved in a quart of water, and the solution is poured into a vase of a spherical shape. A stopper for this vase is made out of a piece of zinc, to which five or six separate brass wires are attached; these are plunged into the fluid, and we see the wires become immediately covered with brilliant crystallized spangles of lead, which continue increasing in size. The alchemists, who were familiar with this experiment, believed that it consisted in a transformation of copper into lead, while in reality it only Fig. 313.—Representation of bars of metal, all of the same weight. Copper, when it is pure, has a characteristic red colour, which prevents it being confounded with any other metal; it dissolves easily in nitric acid, and with considerable effervescence, giving off vapour very abundantly. This property has been put to good use in engraving with aqua fortis. A copper plate is covered with a layer of varnish, and when it is dry some strokes are made on it by means of a graver; if nitric acid is poured on the plate when thus prepared, the copper is only acted on in the parts that have been exposed by the point of steel. By afterwards removing the varnish, we have an engraved plate, which will serve for printing purposes. Fig. 314.—Tree of Saturn. Among experiments that may be attempted with common metals, we may mention that in which salts of tin are employed. Tin has a great tendency to assume a crystalline form, and it will be easy to show this property by an interesting experiment. A concentrated solution of proto-chloride of tin, prepared by dissolving some metallic tin in hydrochloric acid, is placed in a test glass; then a rod of tin is introduced, as shown in fig. 315. Some water is next slowly poured on the rod, so that it gradually trickles down, and prevents the mingling of the proto-chloride of tin. The vessel is then left to stand, and we soon see brilliant crystals starting out from the rod. This crystallization is not effected in the water; it is explained by an electric influence, into the details of which we cannot enter without overstepping our limits; it is known as “Jupiter’s Tree.” It is well known that alchemists, with their strange system of nomenclature, believed there was a certain mysterious relation between the seven metals then known and the seven planets; each metal was dedicated to a planet; tin was called Jupiter; silver, When speaking of precious metals, we may call to mind that the alchemists considered gold as the king of metals, and the other valuable ones as noble metals. This definition is erroneous, if we look upon the useful as the most precious; for, in that case, iron and copper would be placed in the first rank. If gold were found abundantly on the surface of the soil, and iron was extremely rare, we should seek most eagerly for this useful metal, and should despise the former, with which we can neither make a ploughshare nor any other implement of industry. Nevertheless, the scarcity of gold, its beautiful yellow colour, and its unalterability when in contact with air, combine to place it in the first rank in the list of precious metals. Gold is very heavy; its density is represented by the figure 19·5. It is the most malleable and the most ductile of metals, and can be reduced by beating to such thin sheets that ten thousand can be laid, one over the other, to obtain the thickness of a millimetre. With a grain of gold a thread may be manufactured extending a league in length, and so fine that it resembles a spider’s web. When gold is beaten into thin sheets it is no longer opaque; if it is fastened, by means of a solution of gum, on to a sheet of glass, the light passes right through it, and presents a very perceptible green shade. Gold is sometimes found scattered in sand, in a condition of impalpable dust, and, in certain localities, in irregular lumps of varying size, called nuggets. Gold is the least alterable of the metals, and can be exposed, indefinitely, to the contact of humid atmosphere without oxidizing. It is not acted on by the most powerful acids, and only dissolves in a mixture of nitric acid and hydrochloric acid. We can prove that gold resists the influence of acids by the following operation:— Some gold-leaf is placed in two small phials, the first containing hydrochloric acid, and the second nitric acid. The two vessels are warmed on the stove, and whatever the duration of the ebullition of the acids, the gold-leaf remains intact, and completely resists their action. If we then empty the contents of one phial into the other, the hydrochloric and nitric acids are mixed, and we see the gold-leaf immediately disappear, easily dissolved by the action of the liquid (aqua regia). Gold also changes when in contact with mercury; this is proved by suspending some gold-leaf above the surface of this liquid (fig. 316); it quickly changes, and unites with the fumes of the mercury, becoming of a greyish colour. Silver is more easily affected than gold, and though so white when fused, tarnishes rapidly in contact with air. It does not oxidize, but sulphurizes under the influence of hydro-sulphuric emanations. Silver does not combine directly with the oxygen of the atmosphere; but under Fig. 315.—Jupiter’s Tree. Nitric acid dissolves silver very easily, by causing the formation of abundant fumes. When the solution evaporates, we perceive white crystals forming, which are nitrate of silver. This fused nitrate of silver takes the name of lunar caustic, and is employed in medicine. Nitrate of silver is very poisonous; it possesses the singular property of turning black under the action of the sun’s rays, and is used in many curious operations in photography. It is also employed in the manufacture of dyes for the hair; it is applied to white hair with gall-nut, and under the influence of the light it turns black, and gives the hair a very dark shade. Salts of silver in solution with water have the property of forming a precipitate under the influence of chlorides, such as sea salt. If a few grains of common salt are thrown into a solution of nitrate of silver, it forms an abundant precipitate of chloride of silver, which blackens in the light. This precipitate, insoluble in nitric acid, dissolves very easily in ammonia. Platinum, which is the last of the precious metals that we have to consider, is a greyish-white colour, and like gold is only affected by a mixture of nitric acid and hydrochloric acid. It is the heaviest of all the Fig. 316.—Gold-leaf exposed to the fumes of mercury. A very ingenious little lamp may be constructed which lights of itself without the help of a flame. It contains a bell of glass, which is filled with hydrogen gas, produced by the action exercised by a foundation of zinc on acidulated water. If the knob on the upper part of the apparatus is pressed, the hydrogen escapes, and comes in contact with a piece of spongy platinum, which, acting by oxidation, becomes ignited. The flame produced sets fire to a small oil lamp, which is opposite the jet of gas. This very ingenious lamp is known under the name of Gay-Lussac’s lamp. Platinum can also produce, by mere contact, a great number of chemical reactions. Place in a test glass an explosive mixture formed of two volumes of hydrogen and one volume of oxygen; in this gas plunge a small piece of spongy platinum, Fig. 317.—Discolouration of periwinkles by sulphuric acid. Artificial Colouring of Flowers. In a course of chemistry, the action exercised by sulphurous acid on coloured vegetable matter is proved by exposing violets to the influence of this gas, which whitens them instantaneously. Sulphurous acid, by its dis-oxidating properties, destroys the colour of many flowers, such as roses, periwinkles, etc. The experiment succeeds very readily by means of the little apparatus which we give in fig. 317. We dissolve in a small vessel some sulphur, which ignites in contact with air, and gives rise, by its combination with oxygen, to sulphurous acid; the capsule is covered with a conical chimney, made out of a thin sheet of copper, and at the opening at the top the flowers that are to be discoloured are placed. The action is very rapid, and a few seconds only are necessary to render roses, periwinkles, and violets absolutely white. Fig. 318.—Experiment for turning columbines a green colour with ammoniacal ether. M. Filpol, a distinguished savant, has exhibited to the members of the Scientific Association, Paris, the results which he obtained by subjecting flowers to the influence of a mixture of sulphuric ether and some drops of ammonia; he has shown that, under the influence of this liquid, a great number of violets or roses turn a deep green. We have recently made on this subject a series of experiments which we will here describe, and which may be easily attempted by those of our readers who are interested in the The most singular changes of colour are shown by flowers which are composed of different tints, their red streaks turning green, the white yellow, etc. Another curious example is that of red and white fuchsias, which, through the action of ammonia, turn yellow, blue, and green. When flowers have been subjected to these changes of colour, and afterwards plunged into pure water, they preserve their new tint for several hours, after which they gradually return to their natural colour. Another interesting observation, due to M. Gabba, is that asters, which are naturally inodorous, acquire an agreeable aromatic odour under the influence of ammonia. Asters of a violet colour become red when wetted with nitric acid mixed with water. On the other hand, if these same flowers are enclosed in a wooden box, where they Phosphorescence. Artificial flowers are frequently to be seen prepared in a particular manner, which have the property of becoming phosphorescent in darkness, when they have been exposed to the action of a ray of light, solar or electric. These curious chemical objects are connected with some very interesting phenomena and remarkable experiments but little known at the present time, to which we will now draw the reader’s attention. The faculty possessed by certain bodies of emitting light when placed in certain conditions, is much more general than is usually supposed. M. Edmond Becquerel, to whom we owe a remarkable work on this subject, divides the phenomena of phosphorescence into five distinct classes: 1. Phosphorescence through elevation of temperature. Among the substances which exhibit this phenomenon in a high degree we may mention certain diamonds, coloured varieties of fluoride of calcium, some minerals; and sulphur, known under the name of artificial phosphorus, when it has previously been exposed to the action of the light. 2. Phosphorescence through mechanical action. This is to be observed when we rub certain bodies together, or against a hard substance. If we rub together two quartz crystals in the dark, we perceive red sparks; and when pounding chalk or sugar, there is also an emission of sparks. 3. Phosphorescence through electricity. This is manifested by the light accompanying disengagement of electricity, and when gases and rarefied vapours transmit electric discharges. 4. Spontaneous Phosphorescence is observed, as every one knows, in connection with several kinds of living creatures,—glow-worms, noctilucids, etc., and similar phosphorescent effects are produced also with organic substances, animal or vegetable, before putrefaction sets in. It is manifested also at the flowering time of certain plants, etc. 5. Phosphorescence through insolation and the action of light. “It consists,” says M. Edmond Becquerel, “in exposing for some instants to the action of the sun, or to that of rays emanating from a powerful luminous source, certain mineral or organic substances, which immediately become luminous, and shine in the dark with a light, the colour and brilliancy of which depend on their nature and physical character; the light gradually diminishes in intensity during a period varying from some seconds to several hours. When these substances are exposed anew to the action of light, the same effect is Fig. 319.—Artificial flower coated with phosphorescent powder, exposed to the light of magnesium wire. Phosphorescent sulphate of calcium is prepared by calcining in an earthenware crucible a mixture of flowers of sulphur and carbonate of lime. But the preparation only succeeds with carbonate of lime of a particular character. That obtained from the calcination of oyster shells produces very good results. Three parts of this substance is mixed with one part of flowers of sulphur, and is made red-hot in a crucible covered in from contact with the air. The substance thus obtained gives, after its insolation, a yellow light in the dark. The shells of oysters, however, are not always “When we desire to prepare a phosphorescent sulphate with lime, or carbonate of lime,” says M. E. Becquerel, “the most suitable proportions are those which in a hundred parts of the substance are composed of eighty to a hundred of flowers of sulphur in the first case, and forty-eight to a hundred in the second, that is, when we employ the quantity of sulphur which will be necessary for burning with carbonate of lime to produce a monosulphate.20 It is necessary to have regard to the elevation of the temperature in the preparation. By using lime procured from arragonite, and reducing the temperature below five hundred degrees for a sufficient time for the reaction between the sulphur and lime to take place, the excess of sulphur is eliminated, and we have a feebly luminous mass, of a bluish tint; if this mass is raised to a temperature of eight hundred or nine hundred degrees, it will exhibit a very bright light.” Sulphate of calcium possesses different phosphorescent properties according to the nature of the salt which has served to produce the carbonate of lime employed. If we transform marble into nitrate of lime, by dissolving it in water and nitric acid, and form a precipitate with carbonate of ammonium, and use the carbonate of lime thus obtained in the preparation of sulphate of calcium, we have a product which gives a phosphorescence of a violet-red colour. If the carbonate of lime used is obtained from chloride of calcium precipitated by carbonate of ammonia, the phosphorescence is yellow. If we submit carbonate of lime, prepared with lime water and carbonic acid, to the influence of sulphur, we obtain a sulphur giving a phosphorescent light of very pure violet. Carbonate of lime obtained by forming a precipitate of crystallized chloride of calcium with different alkaline carbonates also gives satisfactory results. Luminous sulphates of strontium may be obtained, like those of calcium, by the action of sulphur on strontia or the carbonate of this base, by the reduction of sulphates of strontia with charcoal. Blue and green shades are the most common. Sulphates of barium also present very remarkable phenomena of phosphorescence; but to obtain very luminous intensity a higher temperature is needed than with the other substances mentioned, and we have the same result when we reduce native sulphate of baryta with charcoal; that is to say, when the reaction takes place which produces the phosphorus formerly known as phosphorus of Bologna. Preparations obtained from baryta have a phosphorescence varying from orange-red to green. The preparation of such substances as we have just enumerated afford an easy explanation of the method of manufacturing the luminous flowers which we described at the commencement of this chapter. We obtain some artificial flowers, cover them with some liquid gum, sprinkle with phosphorescent sulphur, and let them dry. The pulverulent matter then adheres to them securely, and it is only necessary to expose the flowers But let us ask ourselves if these substances are not capable of being put to more serious uses, and of being classed among useful products. To this we can reply very decidedly in the affirmative. With phosphorescent matter we can obtain luminous faces for clocks placed in dark, obscure spots, and it is not impossible to use it for making sign-boards for shops, or numbers of houses, which can be lit up at night. Professor Norton even goes so far as to propose in the “Journal of the Franklin Institute,” not only coating the walls of rooms with these phosphorescent substances, but also the fronts of houses, when he considers it would be possible to do away entirely with street lights, the house-fronts absorbing sufficient light during the day to remain luminous the whole of the night. Chemistry Applied to Sleight of Hand. While physics has provided the species of entertainment called “sleight of hand” with a number of interesting effects, chemistry has only offered it very feeble contributions. Robert Houdin formerly made use of electricity to move the hands of his magic clock, and the electric magnet in making an iron box so heavy instantaneously that no one could lift it. Robin has made use of optics to produce the curious spectacle of the decapitated man, spectres, etc. Those persons who are fond of this kind of amusement may, however, borrow from chemistry some original experiments, which can be easily undertaken, and I will conclude this chapter by describing a juggling feat which I have seen recently executed before a numerous audience by a very clever conjuror. Fig. 321.—Amusing experiment in chemistry. The operator took a glass that was perfectly transparent, and placed it on a table, announcing that he should cover the glass with a saucer, and then, retiring to some distance, would fill it with the smoke from a cigarette. And this he carried out exactly, standing smoking his cigarette in the background, while the glass, as though by enchantment, slowly filled with the fumes of the smoke. This trick is easily accomplished. It is only necessary to pour previously into the glass two or three drops of hydrochloric acid, and to moisten the bottom of the saucer with a few drops of ammonia. These two liquids are unperceived by the spectators, but as soon as the saucer is placed over the glass, they unite in forming white fumes of hydrochlorate of ammonia, which bear a complete resemblance to the smoke of tobacco. This experiment excited the greatest astonishment among the spectators present on the occasion, but understanding something of chemistry myself, I easily guessed at the solution of the mystery. The same result is obtained in a course of chemistry in a more simple manner, and without any attempt at trickery, by placing the opening of a bottle of ammonia against the opening of another bottle containing hydrochloric acid. Decoration |