[1] The opening lecture was twice postponed on account of Dr. Faraday's illness.
[2] Platinum, with one exception the heaviest body known, is 21 1/2 times heavier than water.
[3] Aluminium is 2 1/2 times heavier than water.
[4] Power or property in water. This power - the heat by which the water is kept in a fluid state - is said, under ordinary circumstances, to be latent or insensible. When, however, the water changes its form, and, by uniting with the lime or sulphate of copper, becomes solid, the heat which retained it in a liquid state is evolved.
[5] Anhydrous sulphate of copper: sulphate of copper deprived of its water of crystallization. To obtain it the blue sulphate is calcined in an earthen crucible.
[6] Add a little liquid to the marble and decompose it. Marble is composed of carbonic acid and lime, and, in chemical language, is called carbonate of lime. When sulphuric acid is added to it, the carbonic acid is set free, and the sulphuric acid unites with the lime to form sulphate of lime. Carbonic acid, under ordinary circumstances, is a colorless invisible gas, about half as heavy again as air. Dr. Faraday first showed that under great pressure it could be obtained in a liquid state. Thilorier, a French chemist, afterward found that it could be solidified.
[7] Crystallization of alum. The solution must be saturated - that is, it must contain as much alum as can possibly be dissolved. In making the solution, it is best to add powdered alum to hot water as long as it dissolves; and when no more is taken up, allow the solution to stand a few minutes, and then pour it off from the dirt and undissolved alum.
[8] Red precipitate of biniodide of mercury. A little care is necessary to obtain this precipitate. The solution of iodide of potassium should be added to the solution of perchloride of mercury (corrosive sublimate) very gradually. The red precipitate which first falls is redissolved when the liquid is stirred: when a little more of the iodide of potassium is added a pale red precipitate is formed, which, on the farther addition of the iodide, changes into the brilliant scarlet biniodide of mercury. If too much iodide of potassium is added, the scarlet precipitate disappears, and a colorless solution is left.
[9] Paper coated with scarlet biniodide of mercury. In order to fix the biniodide on paper, it must be mixed with a little weak gum water, and then spread over the paper, which must be dried without heat. Biniodide of mercury is said to be dimorphous; that is, is able to assume two different forms.
[10] "Prince Rupert's Drops." These are made by pouring drops of a melted green glass into cold water. They were not, as is commonly supposed, invented by Prince Rupert, but were first brought to England by him in 1660. They excited a great deal of curiosity, and were considered "a king of miracle in nature."
[11] Thick glass vessels - They are called Proofs or Bologna phials.
[12] Mica. A silicate of alumina and magnesia. It has a bright metallic lustre; hence its name, from mico, to shine.
[13] Common salt or chloride of sodium crystallizes in the form of solid cubes, which, aggregated together, form a mass, which may be broken up into the separate cubes.
[14] Iceland or calc-spar. Native carbonate of lime in its primitive crystalline form.
[15] Solution of a salt. Acetate of soda. A solution saturated, or nearly so, at the boiling point, is necessary, and it must be allowed to cool, and remain at rest until the experiment is made.
[16] Binoxide of nitrogen and hyponitrous acid. Binoxide of nitrogen is formed when nitric acid and a little water are added to some copper turnings. It produces deep red fumes as soon as it comes in contact with the air, by combining with the oxygen of the latter to form hyponitrous acid. Binoxide of nitrogen is composed of two parts of oxygen and one part of nitrogen; hyponitrous acid is composed of one part of nitrogen and three parts of oxygen.
[17] 'Ydwp, "water," and yevvaw, "I generate."
[18] Chlorate of potash and sulphuret of antimony. Great care must be taken in mixing these substances, as the mixture is dangerously explosive. They must be powdered separately and mixed together with a feather on a sheet of paper, or by passing them, several times through a small sieve.
[19] The mixture of chlorate of potash and sugar does not require the same precautions. They may be rubbed together in a pestle and mortar without fear. One part of chlorate of potash and three parts of sugar will answer. The mixture need only be touched with a glass rod dipped in oil of vitriol.
[20] Two salts dissolved in water. Sulphate of soda and chloride of calcium. The solutions must be saturated for the experiment to succeed well.
[21] Lead pyrophorus. This is tartrate of lead which has been heated in a glass tube to dull redness as long as vapors are emitted. As soon as they cease to be evolved the end of the tube is sealed, and it is allowed to cool.
[22] Guncotton is made by immersing cotton wool in a mixture of sulphuric acid and the strongest nitric acid or of sulphuric acid and nitrate of potash.
[23] Paper prepared like guncotton. It should be bibulous paper, and must be soaked for ten minutes in a mixture of ten parts, by measure, of oil of vitriol with five parts of strong fuming nitric acid. The paper must afterward be thoroughly washed with warm distilled water, and then carefully dried at a gentle heat. The paper is then saturated with chlorate of strontia, or chlorate of baryta, or nitrate of copper, by immersion in a warm solution of these salts (See Chemical News, vol. i., p. 36.)
[24] Sulphindigotic acid. A mixture of one part of indigo and fifteen parts of concentrated oil of vitriol. It is bleached on the side at which hydrogen gas is evolved in consequence of the liberated hydrogen withdrawing oxygen from the indigo, thereby forming a colorless deoxidized indigo. In making the experiment, only enough of the sulphindigotic acid must be added to give the water a decided blue color.
[25] Lead tree. To make a lead tree, pass a bundle of brass wires through the cork of a bottle, and fasten a plate of zinc round them just as they issue from the cork, so that the zinc may be in contact with every one of the wires. Make the wires to diverge so as to form a sort of cone, and, having filled the bottle quite full of a solution of sugar of lead, insert the wires and cork, and seal it down, so as to perfectly exclude the air. In a short time the metallic lead will begin to crystallize around the divergent wires, and form a beautiful object.