Notes
The Force of Matter / Lecture I.—The Force of Gravitation
Platinum, with one exception the heaviest body known, is 21 1/2 times heavier than water.
Aluminium is 2 1/2 times heavier than water.
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.
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.
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.
The Force of Matter / Lecture II.—Gravitation—Cohesion
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.
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.
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.]
“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.”
Thick glass vessels. They are called Proofs or Bologna phials.
Mica. A silicate of alumina and magnesia. It has a bright metallic lustre; hence its name, from mico, to shine.
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.
Iceland or calc-spar. Native carbonate of lime in its primitive crystalline form.
The Force of Matter / Lecture III.—Cohesion—Chemical Affinity
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.
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.
The Force of Matter / Lecture IV.—Chemical Affinity—Heat
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.
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.
Two salts dissolved in water. Sulphate of soda and chloride of calcium. The solutions must be saturated for the experiment to succeed well.
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.
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.
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.)
The Force of Matter / Lecture VI.—The Correlation of the Physical Forces
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.
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.
The Chemical History of a Candle / Lecture I.—A Candle: The Flame—Its Sources—Structure—Mobility—Brightness
The Royal George sunk at Spithead on the 29th of August, 1782. Colonel Pasley commenced operations for the removal of the wreck by the explosion of gunpowder, in August 1839. The candle which Professor Faraday exhibited must therefore have been exposed to the action of salt water for upward of fifty-seven years.
The fat or tallow consists of a chemical combination of fatty acids with glycerin. The lime unites with the palmitic, oleic, and stearic acids, and separates the glycerin. After washing, the insoluble lime soap is decomposed with hot dilute sulphuric acid. The melted fatty acids thus rise as an oil to the surface, when they are decanted. They are again washed and cast into thin plates, which, when cold, are placed between layers of cocoanut matting and submitted to intense hydraulic pressure. In this way the soft oleic acid is squeezed out, while the hard palmitic and stearic acids remain. These are farther purified by pressure at a higher temperature and washing in warm dilute sulphuric acid, when they are ready to be made into candles. These acids are harder and whiter than the fats from which they were obtained, while at the same time they are cleaner and more combustible.
A little borax or phosphorus salt is sometime added in order to make the ash fusible.
Capillary attraction or repulsion is the cause which determines the ascent or descent of a fluid in a capillary tube. If a piece of thermometer tubing, open at each end, be plunged into water, the latter will instantly rise in the tube considerably above its external level. If, on the other hand, the tube be plunged into mercury, a repulsion instead of attraction will be exhibited, and the level of the mercury will be lower in the tube than it is outside.
The late Duke of Sussex was, we believe, the first to show that a prawn might be washed upon this principle. If the tail, after pulling off the fan part, be placed in a tumbler of water, and the head be allowed to hang over the outside, the water will be sucked up the tail by capillary attraction, and will continue to run out through the head until the water in the glass has sunk so low the tail ceases to dip into it.
The alcohol had chloride of copper dissolved in it: this produces a beautiful green flame.
The Chemical History of a Candle / Lecture II.—A Candle: Brightness of the Flames—Air Necessary for Combustion—Production of Water
Lycopodium is a yellowish powder found in the fruit of the club moss (Lycopodium clavatum). It is used in fireworks.
Bunsen has calculated that the temperature of the oxyhydrogen blowpipe is 8061° Centigrade. Hydrogen burning in air has a temperature of 3259° C., and coal gas in air, 2350° C.
The following is the action of the sulphuric in inflaming the mixture of sulphuret of antimony and chlorate of potassa. A portion of the latter is decomposed by the sulphuric acid into oxide of chlorine, bisulphate of potassa, and perchlorate of potassa. The oxide of chlorine inflames the sulphuret of antimony, which is a combustible body, and the whole mass instantly bursts into flame.
The “air-burner,” which is of such value in the laboratory, owes its advantage to this principle. It consists of a cylindrical metal chimney, covered at the top with a piece of rather coarse iron wire gauze. This is supported over an Argand burner in such a manner that the gas may mix in the chimney with an amount of air sufficient to burn the carbon and hydrogen simultaneously, so that there may be no separation of carbon in the flame with consequent deposition of soot. The flame, being unable to pass through the wire gauze, burns in a steady, nearly invisible manner above.
The Chemical History of a Candle / Lecture III.—Products: Water from the Combustion—Nature of Water—A Compound—Hydrogen
Water is in its densest state at a temperature of 39.1° Fahrenheit.
A mixture of salt and pounded ice reduces the temperature from 32° F. to zero, the ice at the same time becoming fluid.
Potassium, the metallic basis of potash, was discovered by Sir Humphry Davy in 1807, who succeeded in separating it from potash by means of a powerful voltaic battery. Its great affinity for oxygen causes it to decompose water with evolution of hydrogen, which takes fire with the heat produced.
Professor Faraday has calculated that there is as much electricity required to decompose one grain of water as there is in a very powerful flash of lightning.
The Chemical History of a Candle / Lecture IV.—Hydrogen in the Candle—Burns into Water—The Other Part of Water—Oxygen
A solution of acetate of lead submitted to the action of the voltaic current yields lead at the negative pole, and brown peroxide of lead at the positive pole. A solution of nitrate of silver, under the same circumstances, yields silver at the negative pole, and peroxide of silver at the positive pole.
The Chemical History of a Candle / Lecture V.—Oxygen Present in the Air—Nature of the Atmosphere—Its Properties—Other Products from the Candle—Carbonic Acid—Its Properties
The gas which is thus employed as a test for the presence of oxygen is the binoxide of nitrogen, or nitrous oxide. It is a colorless gas, which, when brought in contact with oxygen, unites with it, forming hyponitric acid, the red gas referred to.
Marble is a compound of carbonic acid and lime. The muriatic acid, being the stronger of the two, takes the place of the carbonic acid, which escapes as a gas, the residue forming muriate of lime or chloride of calcium.
The Chemical History of a Candle / Lecture VI.—Carbon or Charcoal—Coal-Gas—Respiration and its Analogy to the Burning of a Candle—Conclusion
Lead pyrophorus is made by heating dry tartrate of lead in a glass tube (closed at one end, and drawn out to a fine point at the other) until no more vapors are evolved. The open end of the tube is then to be sealed before the blowpipe. When the tube is broken and the contents shaken out into the air, they burn with a red flash.
On the Conservation of Force
This is the technical measure of work; to convert it into scientific measure it must be multiplied by the intensity of gravity.
The measure of vis viva in theoretical mechanics is half the product of the weight into the square of the velocity. To reduce it to the technical measure of the work we must divide it by the intensity of gravity; that is, by the velocity at the end of the first second of a freely falling body.
Ice and Glaciers
In the Lecture a series of small cylinders of ice, which had been prepared by a method to be afterwards described, were pressed with their plane ends against each other, and thus a cylindrical bar of ice produced.
Vide the additions at the end of this Lecture.
In this experiment the lower temperature of the compressed ice sometimes extended so far through the iron form, that the water in the slit between the base plate and the cylinder froze and formed a thin sheet of ice, although the pieces of ice as well as the iron mould had previously laid in ice water, and could not be colder than 0°.
These cracks are probably quite empty and free from air, for they are also formed when perfectly clear and air-free pieces of ice are pressed in the form which has been previously filled with water, and where, therefore, no air could gain access to the pieces of ice. That such air-free crevices occur in glacier ice has been already demonstrated by Tyndall. When the compressed ice afterwards melts, these crevices fill up with water, no air being left. They are then, however, far less visible, and the whole block is therefore clearer. And just for this reason they could not originally have been filled with water.]
The Wave Theory of Light
Alluding to a moving diagram of wave motion of sound produced by a working slide for lantern projection.
Showing two moving diagrams, simultaneously, on the screen, one depicting a wave motion of light, the other a sound vibration.
Exhibiting a large drawing, or chart, representing a red and a violet wave of light (reproduced in Figs. 118 and 119).
Since my lecture I have heard from Professor Langley that he has measured the refrangibility by a rock salt prism, and inferred the wave-length of heat rays from a “Leslie cube” (a metal vessel filled with hot water and radiating heat from a blackened side). The greatest wave-length he has thus found is one-thousandth of a centimetre, which is seventeen times that of sodium light—the corresponding period being about thirty million million per second.—November, 1884.—W. T.
Exhibiting a large bowl of clear jelly with a small red wooden ball embedded in the surface near the centre.
Showing the chromatic bands thrown upon the screen from a diffraction grating.
The Tides
The various instruments and tide-curves referred to in this lecture are fully described and illustrated in a paper on “The Tide Gauge, Tidal Harmonic Analyser, and Tide Predicter,” read before the Institution of Civil Engineers, on 1st March, 1881, and published in their Proceedings for that date.
Note of September 17, 1887. On the subject of Tidal Harmonic Analysis see “Manual of Instructions for Tidal Observation,” by Major Baird, published by Messrs. Taylor and Francis, London 1886; also the Reports of the British Association Committee “On Harmonic Analysis of Tidal Observations.”—W. T.
Vide vol. xxiv. p. 262, and vol. xxvii. p. 371.
Proc. Royal Society, June 17, 1869; (vol. xviii. p. 72).
Geographical Evolution
A Lecture delivered at the Evening Meeting of the Royal Geographical Society, 24th March, 1879.