BAILYTA CLASS. - The high price of red lead, and various disadvantages connected with its use, have given rise to many efforts to find an efficient substitute for it ,in the manufacture of table and ornamental glass. Barium compounds, principally the native sulphate (common baryta or heavy spar) and the artificially prepared carbonate, have been more or less experimentally tried ever since ; but of late years the use of baryta has attracted much attention, and in several French and Belgian glass-works it is understood to have taken its place as a raw material, without, however, much being publicly said regarding the subject. H. E. Benrath, the scientific director of the Lisette glass-works near Dorpat has investigated the application of baryta in glass-making with great fulness. Baryta, it appears, can be used as a partial substitute for the alkalies in glass-making ; and indeed it was affirmed by Peligot that carbonate of baryta could altogether supplant either potash or soda, and yield a glass perfectly free of alkali. Such a glass is, however, shown by Benrath to be without practical value ; but he has demonstrated that baryta may be used in the place of either lead or lime, to produce an easily fused dense glass much more brilliant than common glass, and in appearance and properties intermediate between that and flint glass. The qualities of the glass and its usefulness for various purposes can be modified by using both baryta and lime in varying proportions. There seems little doubt that baryta will occupy an important place in the future of the glass industry.

circumstances have much influence in determining the class of materials used. In Continental bottle works lava, basalt, and similar rocks of volcanic origin were formerly employed; and in 1)en - mark and Sweden fluoride of calcium, left as a waste product of the manufacture of soda from eryolite, is used with marked advantage.

For bottle-making the tank furnace with or without compartments as already described is much used ; but pot furnaces also continue in use. The arrangements of a common bottle house are seen in fig. 19, which is a ground-plan indicating a bilateral

The following is an outline of the process of making a CO111111011 bottle. After the metal has been skinnned, the person who begins the work is the gatherer, who, heating the pipe, gathers on it a small quantity of metal. After allowing this to cool a little, he again gathers such a quantity as he conceives to be sufficient to make a bottle. This is then handed to the blower, who, while blowing through the tube, rolls the metal upon a stone, at the same time forming the neck of the bottle. Ile then puts the metal into a brass or cast-iron mould of the shape of the bottle wanted, and, continuing to blow through the tube, brings it to the desired form. The patent mould now in use is made of brass, the inside finely polished, divided into two pieces, which the workman, by pressing a spring with his foot, opens and shuts at pleasure. The blower then hands it to the finisher, who touches the neck of the bottle with a small piece of iron dipt in water, which cuts it completely off front the pipe. lie next attaches the runty, on which is a little metal gathered from the pot, to the bottom of the bottle, and thereby gives it the shape which • it usually presents. This Aunty may be used for from 18 to 24 dozen of bottles. It is occasionally dipped into sand to prevent its adhering to the bottle. The finisher then warms the bottle at the furnace, and taking out a small quantity of metal on what is termed a ring iron, he turns it once round the mouth, forming the ring seen at the mouth of bottles. Ile then employ's the shears to give shape to the neck. One of the blades of the shears has a piece of brass in the centre, tapered like ;1 common cork, which forms the inside mouth ; to the other blade is attached a piece of brass, used to form the ring. The bottle is then lifted by the neck on a fork by a boy, and carried to tlef annealing arch, where the bottles are placed in bins above one another. This arch is kept a little below melting beat, till the whole quantity, which amounts to 10 or 12 gross in each arch, is deposited, when the tire is allowed to die out.