"The importance of glass, and the infinite variety of objects to which it is applicable, cannot be exaggerated; indeed, it would be extremely difficult to enumerate its properties, or estimate adequately its value. This, then, transparent substance, so light and fragile, is one of the most essential ministers of science and philosophy, and enters so minutely into the concerns of life that it has become indispensable to the daily routine of our business, our wants, and our pleasures. It admits the sun and excludes the wind, answering the double purpose of transmitting light and preserving warmth; it carries the eye of the astronomer to the remotest regions of space; through the lenses of the microscope it develops new worlds of vitality, which, without its help, must have been but imperfectly known; it renews the sight of the old, and assists the curiosity of the young; it empowers the mariner to descry distant ships, and trace far off shores; the watchman on the cliff to detect the operations of hostile fleets and midnight contrabandists, and the lounger in the opera to make the tour of the circles from his stall; it preserves the light of the beacon from the rush of the tempest, and softens the flame of the lamp upon our tables; it supplies the revel with those charming vessels in whose bright depths we enjoy the color as well as the flavor of our wine; it protects the dial whose movements it reveals; it enables the student to penetrate the wonders of nature, and the beauty to survey the marvels of her person; it reflects, magnifies, and diminishes; as a medium of light and observation its uses are without limit, and as an article of mere embellishment, there is no form into which it may not be moulded, or no object of luxury to which it may not be adapted."

In contrast with the foregoing, we will make one more extract, from an English writer of ancient date. Holinshed, in his "Chronicles," published during the reign of Elizabeth, says:—

"It is a world to see in these our days, wherein gold and silver aboundeth, that our gentility, as loathing these metals, (because of the plenty,) do now generally choose rather the Venice Glasses, both for our wine and beer, than any of these metals, or stone, wherein before time we have been accustomed to drink; but such is the nature of man generally, that it most coveteth things difficult to be attained; and such is the estimation of this stuff, that many become rich only with their new trade into Murana, (a town near to Venice,) from whence the very best are daily to be had, and such as for beauty do well near match the Crystal or the ancient Murrhina Vase, whereof now no man has knowledge. And as this is seen in the gentility, so in the wealthy commonality the like desire of glasses is not neglected, whereby the gain gotten by their purchase is much more increased, to the benefit of the merchant. The poorest endeavor to have glasses also if they may; but as the Venetian is somewhat too dear for them, they content themselves with such as are made at home of fern and burnt stone; but in fine, all go one way, that is to the shades, at last."

PROPERTIES OF GLASS.

Glass has properties peculiarly its own; one of which is that it is of no greater bulk when hot, or in the melted state, than when cold. Some writers state that it is (contrary to the analogy of all other metals) of greater bulk when cold than when hot.

It is transparent in itself; but the materials of which it is composed are opaque. It is not malleable, but in ductility ranks next to gold. Its flexibility, also, is so great that when hot it can be drawn out, like elastic thread, miles in length, in a moment, and to a minuteness equal to that of the silk-worm. Brittle, also, to a proverb, it is so elastic that it can be blown to a gauze-like thinness, so as easily to float upon the air. Its elasticity is also shown by the fact that a globe, hermetically sealed, if dropped upon a polished anvil, will recoil two thirds the distance of its fall, and remain entire until the second or third rebound. (The force with which solid balls strike each other may be estimated at ten, and the reaction, by reason of the elastic property, at nine.) Vessels, called bursting-glasses, are made of sufficient strength to be drawn about a floor; a bullet may be dropped into one without fracture of the glass; even the stroke of a mallet sufficiently heavy to drive a nail has failed to break such glasses. In a word, ordinary blows fail to produce an impression upon articles of this kind. If, however, a piece of flint, cornelian, diamond, or other hard stone, fall into one of these glasses, or be shaken therein a few moments, the vessel will fly into a myriad of pieces.

Glass of the class called Prince Rupert Drops exhibits another striking property. Let the small point be broken, and the whole flies with a shock into powder. Writers have endeavored to solve the philosophy of this phenomenon; some by attributing it to percussion putting in motion some subtle fluid with which the essential substance of glass is permeated, and thus the attraction of cohesion being overcome. Some denominate the fluid electricity, and assert that it exists in glass in great quantities, and is capable of breaking glass when well annealed. These writers do not appear to have formed any conclusion satisfactory to themselves, and fail to afford any well-defined solution to the mystery.

Another phenomenon in connection with glass tubes is recorded in the "Philosophical Transactions," No. 476:—

"Place a tube, say two feet long, before a fire, in a horizontal position, having the position properly supported, say by putting in a cork at each end supported by pins for an axis; the rod will acquire a rotary motion round the axis, and also a progressive motion towards the fire, even if the supporters are declined from the fire. When the progressive motion of the tube towards the fire is stopped by any obstacle, the rotation is still continued. When the tubes are placed in nearly an upright position, leaning to the right hand, the motion will be from east to west; but if they lean to the left hand, their motion will be from west to east; and the nearer they are placed to an upright position the less will be their motion either way. If the tubes be placed on a sheet of glass, instead of moving towards the fire they will move from it, and about the axis in a contrary direction from what they did before; nay, they will recede from the fire, and move a little upwards when the plane inclines towards the fire."

Glass is used for pendulums, as not being subject to affections from heat or cold. It is, as is well known, a non-conductor. No metallic condenser possesses an equal power with one of glass. In summer, when moisture fails to collect on a metallic surface, open glass will gather it on the exterior; the slightest breath of air evidently affecting the glass with moisture. Dew will affect the surface of glass while apparently uninfluential upon other surfaces.

The properties of so-called "musical glasses" are strikingly singular. Glass bowls, partly filled with water, in various quantity, will, as is well known, emit musical sounds, varying with the thickness of their edges or lips. When rubbed, too, with a wet finger, gently, the water in the glass is plainly seen to tremble and vibrate.

Bells manufactured of glass have been found the clearest and most sonorous; the vibration of sound extending to a greater degree than in metallic bells.

Glass resists the action of all acids except the "fluoric." It loses nothing in weight by use or age. It is more capable than all other substances of receiving the highest degree of polish. If melted seven times over and properly cooled in the furnace, it will receive a polish rivalling almost the diamond in brilliancy. It is capable of receiving the richest colors procured from gold or other metallic coloring, and will retain its original brilliancy of hue for ages. Medals, too, embedded in glass, can be made to retain forever their original purity and