the fusion process respectively, so that it may shortly be possible to produce vitreous silica in large and perfectly clear blocks. We have already indicated that glass tubing and rod form the basis upon which the glass-worker, with the aid of the blow-pipe or “lamp,” fashions his productions, which, of course, include a great number of scientific instruments and appliances used more especially in the field of chemistry. In another direction also glass tubing serves as a basis for a branch of the glass industry; this is the manufacture of certain classes of glass beads, which are formed by cutting up a heated glass tube of suitable diameter and colour into short, more or less spherical sections. In some cases the colour of the beads is secured by using glass of the desired tint, but in other cases the beads are made of colourless glass, and a colouring substance is placed in the interior of the bead. Solid glass rods are also employed for a variety of purposes; their mode of manufacture is exactly analogous to that of tubing, except that the gathering is drawn out without having first had a hollow space produced at its centre by the blower. In its most attenuated form glass rod becomes glass thread or fibre; this is produced by drawing hot glass very rapidly, the resulting thread being wound on a large wheel. At one time this material found considerable use, since it was found possible to spin and weave the thinnest glass fibres into fabrics which could be used for dress purposes. It is not, however, to be regretted that this fashion has neither extended nor survived, since it was certainly liable to produce serious injury to health. It is a well-known fact that there are few more injurious or even dangerous substances to be inhaled into the human throat and lungs than finely-divided glass; glass fibre, moreover, when subjected to constant bending and wear, is bound to undergo frequent fracture, and the atmosphere of a ball-room, for example, in which several such dresses were worn would soon be contaminated with innumerable fine, sharp particles of glass which would produce an injurious effect on those inhaling them. At the present time glass fibre is used for little else than the “glass wool” required for certain special purposes in chemical laboratories.