How to Clean Carpets on the Floor to Make Them Look Bright.—To a pailful of water add three pints of oxgall, wash the carpet with this until a lather is produced, which is washed off with clean water.
How to Take Out Varnish Spots from Cloth.—Use chloroform or benzine, and as a last resource spirits of turpentine, followed after drying by benzine.
Flour Paste for all Purposes.—Mix 1 pound rye flour in lukewarm water, to which has been added one teaspoonful of pulverized alum; stir until free of lumps. Boil in the regular way, or slowly pour on boiling water, stirring all the time until the paste becomes stiff. When cold add a full quarter pound of common strained honey, mix well (regular bee honey, no patent mixture).
How to Make Liquid Glue.—Take a wide mouthed bottle, and dissolve in it 8 ounces beet glue in 1/2 pint water, by setting it in a vessel of water, and heating until dissolved. Then add slowly 2-1/2 ounces strong nitric acid 36 deg. Baume, stirring all the while. Effervescence takes place, with generation of fumes. When all the acid has been added, the liquid is allowed to cool. Keep it well corked, and it will be ready for use at any time.
How the World is Weighed and Its Density and Mass Computed.—The density, mass, or weight of the earth was found by the observed force of attraction of a known mass of lead or iron for another mass; or of a mountain by the deflection of a torsion thread or plumb line. In this manner the mean density of the earth has been found to be from 4.71 to 6.56 times the weight of water, 5.66 being accredited as the most reliable. The weight of a cubic foot of water being known, and the contents of the earth being computed in cubic feet, we have but to multiply the number of cubic feet by 5.66 times the weight of 1 cubic foot of water to obtain the weight of the earth in pounds, or units of gravity at its surface, which is the unit usually used. Another method of determining the mean density of the earth is founded on the change of the intensity of gravity in descending deep mines.
A Theory as to the Origin of Petroleum.—Professor Mendelejef has recently advanced the theory that petroleum is of purely mineral origin and that the formation of it is going on every day. He has, moreover, succeeded in producing artificial petroleum by a reaction that he describes, and he states that it is impossible to detect any difference between the natural product and the manufactured article. His theory is as follows: Infiltration of water, reaching a certain depth, come into contact with incandescent masses of carburets of metals, chiefly of iron, and are at once decomposed into oxygen and hydrogen. The oxygen unites with the iron, while the hydrogen seizes on the carbon and rises to an upper level, where the vapors are condensed in part into mineral oil, and the rest remains in a state of natural gas. The petroleum strata are generally met with in the vicinity of mountains, and it may be granted that geological upheavals have dislocated the ground in such a way as to permit of the admission of water to great depths. If the center of the earth contains great masses of metallic carburets, we may, in case this theory is verified, count upon an almost inexhaustible source of fuel for the day when our coal deposits shall fail us.
How Vaseline is Purified.—The residuum from which vaseline is made is placed in settling tanks heated by steam, in order to keep their contents in a liquid state. After the complete separation of the fine coke it is withdrawn from these tanks and passed through the bone black cylinders, during which process the color is nearly all removed, as well as its empyreumatic odor.
The Latest and Best Process Employed by Cutters and Others in Etching Names and Designs on Steel.—Take copper sulphate, sulphate of alum and sodium chloride, of each 2 drachms, and strong acetic acid 1-1/2 ounces, mixed together. Smear the metal with yellow soap and write with a quill pen without a split.
The History of the Discovery of Circulation of the Blood recapitulated, divides itself naturally into a series of epoch-making periods: 1. The structure and functions of the valves of the heart, Erasistratus, B.C. 304. 2. The arteries carry blood during life, not air, Galen, A.D. 165. 3. The pulmonary circulation, Servetus, 1553. 4. The systemic circulation, Cæsalpinus, 1593. 5. The pulmonic and systemic circulations, Harvey, 1628. 6. The capillaries, Malpighi, 1661.