(3) To cut glass jars, fill the jar with lard-oil to where you want to cut the jar; then heat an iron rod or bar to red heat, immerse it in the oil; the unequal expansion will crack the jar all round at the surface of the oil, and you can lift off the top part.

(4) The following is said to be an easy way of cutting glass bottles, carboys, etc, into hand-lights. Pass 5 or 6 strands of coarse packing twine round the bottle on each side of where you want it divided, so as to form a groove about 1/8-in. wide; in this groove pass one turn of a piece of hard-laid white line, and extend the two ends, and make them fast to some support; then have a tub of cold water close to you, and, grasping the bottle by the neck with one hand, and the bottom with another, saw the bottle quickly backwards and forwards for a short time; you will soon notice a burning smell caused by the friction of the hard cord. After about one minute's friction, by a side motion of the bottle, throw it out of the line into the water, and then tap against the side of the tub, when the bottom will drop off. Carboys can be cut as easily, but being larger, they require two persons to see-saw them backwards and forwards. The line of twine to form the groove must be put on quite tight, and then wetted to tighten more, so as not to shift; but let the groove and stout cord be dry.

The cutting cord should not be less than 1/8-in. thick; the edge of the glass after cutting, should be rubbed on a grindstone, as it is very sharp.

(5) If a bottle is to be cut into two pieces, a notch is Bled in its side. Then, by applying a hot iron or glass rod, first on one side then on the other of the notch, a smooth crack 1/2-in. long will sometimes form. But as this does not always take place, and, as in Cutting glass only one of the pieces is wanted, a crack may be started well away from the desired place. Assuming such a crack to be formed, it maybe led in any direction by slowly moving in advance of it, and in contact with the glass, the end of a pipestem, of an iron or a glass rod, heated to a full red heat. The speed with which the rod is to be moved depends on the crack. It should be kept about 1/4 in. in advance thereof, and should be moved continually away from the end, as the crack extends itself. In this way a flask can be cut into a spiral, or heavy plate glass divided with fair accuracy.

The great point is to have the line of the cut well marked. If a bottle is to be cut off, to make a battery jar for instance, a string tied or a rubber band sprung around it about 1/4 in. from the place of division forms a convenient guide. The cut may be c irried around parallel with the string or band. Then a half-hour's grinding on a horizontal pane of glass, with sand, camphor, and turpentine, will finish the edge perfectly. In marking the place for cutting, a pointed piece of soap may be used, as a string can only be employed on cylindrical objects. This method of working is attended with one inconvenience. Unless a rod of large size is used, continual reheating is necessary. A glass rod as thick as a penholder will carry a cut about 2 in. at a heat. A pipestem or ten penny nail will do the same. To obviate waiting, several rods may be used, some heating while one is in use.

A fine gas jet, burning from a fine glass jet at the end of a rubber tube, has also been suggested, but is inconvenient. Little carbon pencils, that burn with flameless incandescence, may be used instead of a heated rod. These, however, are troublesome to make.

The use of what is sold by the fireworks dealers under the name of punk was suggested by a consideration of the points given above, This substance burns slowly, without flame, and maintains a strong incandescence until quite consumed. The incandescent part takes the shape of a cone, like a sharpened pencil. As long as the piece lasts, its burning end maintains this form. By blowing upon it the heat can be materially increased. On trial, it was found to cut glass perfectly. The only objection to it is that if rubbed against the glass the ash soils its surface, so that the progress of the crack cannot be conveniently watched. But in practice it is not necessary to hold it in contact with the glass, as it radiates heat enough to lead the crack, if held very close and not in absolute contact therewith.

By using punk the trouble of shifting from rod to rod and the necessity of a source of high heat, a Bunsen burner generally, is obviated. The punk can be lighted with a candle, or even with a match, and is ready for use immediately. A long stick will last for 1/2 hour, enough to do a great deal of work. The only difficulty is in starting the crack. It may be done by heating the glass, and touching it with a drop of water. This generally starts several, and the one pointing in the most convenient direction may be chosen, and carried where desired. The method first spoken of as applicable to bottles, that of filing a notch and heating the glass first on one side and then on the other, cannot be depended on. (S. T.)