1. To a solution of sulphate of iron add a drop or two of a solution of prussiate of potash, and a blue color will be produced. 2. Substitute sulphate of copper for iron, and the color will be a rich brown. 3. Another blue, of quite a different tint, may be produced by letting a few drops or a solution of ammonia fall into one of sulphate of copper--a precipitate of a light blue falls down, which is dissolved by an additional quantity of the ammonia, and forms a transparent solution of the most splendid rich blue color. 4. Into a solution of sulphate of iron let fall a few drops of a strong infusion of galls, and the color will become a bluish-black--in fact, _ink_. A little _tea_ will answer as well as the infusion of galls. This is the reason why certain stuffs formerly in general use for dressing-gowns for gentlemen were so objectionable; for as they were indebted to a salt of iron for their color, buff as it was called, a drop of tea accidentally spilt produced all the effect of a drop of ink. 5. Put into a largish test tube two or three small pieces of granulated zinc, fill it about one-third full of water, put in a few grains of iodine and boil the water, which will at first acquire a dark purple color, gradually fading as the iodine combines with the zinc. Add a little more iodine from time to time, until the zinc is nearly all dissolved. If a few drops of this solution be added to an equally colorless solution of corrosive sublimate (a salt of mercury) a precipitate will take place of a splendid scarlet color, brighter if possible than vermilion, which is also a preparation of mercury. Crystallization of Metals. Some of the metals assume certain definite forms in returning from the fluid to the solid state. Bismuth shows this property more readily than most others. Experiment. Melt a pound or two of bismuth in an iron ladle over the fire; remove it as soon as the whole is fluid; and when the surface has become solid break a hole in it, and pour out the still fluid metal from the interior; what remains will exhibit beautifully-formed crystals of a cubic shape. Sulphur may be crystallized in the same manner, but its fumes, when heated, are so very unpleasant that few would wish to encounter them. One of the most remarkable facts in chemistry, a science abounding in wonders, is the circumstance, that the mere contact of hydrogen, the _lightest_ body known, with the metal platinum, the heaviest, when in a state of minute division, called spongy platinum, produces an intense heat, sufficient to inflame the hydrogen; of course this experiment must be made in the presence of atmospheric air or oxygen. Time and space (or rather the want of them) compel us to conclude with a few experiments of a miscellaneous character. To Form a Solid From Two Liquids. Prepare separately, saturated solutions of sulphate of magnesia (Epsom salts) and carbonate of potash. On mixing them the result will be nearly solid.