The molten glass is collected on the extremity of the blowing-iron to form a ‘gathering.’ This gathering, while still in a soft condition, is rolled upon the ‘marver’ into a cylindrical mass. By blowing down the tube this mass is now distended to form a hollow pear-shaped vesicle, for which it will be convenient to adopt the French term _paraison_. It is from this paraison that a start is made to form by a ‘spinning’ or ‘flashing’ process a sheet of broad or crown glass; again, the vesicle may be made to assume a cylindrical shape, and then opened out to form larger sheets of glass; or finally—and this is for us the most important—by holding the blowing-iron to which the bulb of glass is attached in a vertical position (or sometimes by swinging it over the workman’s head), and then by shaping it by means of certain simple tools, the paraison is started on the course by which it will finally be converted into a bottle or into a bowl-shaped vessel. I will here only dwell on one point. It is evident that so long as the glass is attached to the blowing-iron, although a simple bulb-shaped vessel may be formed, there is so far no means of shaping or finishing the upper portion. Before this can be done the further extremity of the paraison must be attached by means of a small gathering of molten glass to a light tapering rod of iron, the ‘punto’ or ‘pontil.’ The vessel—for so the paraison may now be called—is at this stage removed from the blowing-iron. This is done by ‘wetting it off’ by means of a rod of moistened iron. The glass vessel, now attached by its base to the pontil, is reheated, and the further treatment taken in hand by a workman seated on a stool with long projecting arms, on which (or on the knee of the workman) the pontil is rotated. The shaping is chiefly done by an iron instrument called the ‘procello,’ or spring-tool, formed like a pair of sugar-tongs by two blades connected by an elastic bow. Finally, the edges are finished off by shears and scissors of various forms, which cut the hot glass as if it were a piece of soft leather. The now finished vessel is removed from the pontil by wetting the point of attachment, and is taken to the annealing oven. In this very summary account of the processes involved in making, say, a flask of simple shape, I have only dwelt upon such instruments and methods as have for several centuries been in general use. THE DECAY OF GLASS Before ending this preliminary chapter, a few words may be said of the changes that take place in glass in the course of time from the action of the surrounding medium.[5] These changes are in the main due to the moisture and carbonic acid contained either in the soil or in the atmosphere. Perhaps what is most striking in this action is on the one hand the apparently capricious and irregular way in which the glass is attacked, and on the other the great beauty of the iridescent effects that so often accompany the process of decay.