A very good plan to adopt in moulding is to form the burnt lime into a stiff paste with water, preferably by adding enough water to make a viscous mass, and leaving this in a lime-pit for several weeks, the prolonged storage enabling the lime to acquire the already mentioned fatty character, and at the same time to become highly plastic. Lime treated in this way can be forced through a nozzle, forming a cylindrical rope, which can be cut by a knife into convenient lengths and left on boards for a few days until they have become firm enough to stand up without breaking. Cylinders made in this manner, with a length of about four inches and a diameter of two inches, will absorb carbon dioxide very quickly. The absorption can be still further accelerated by setting up the cylinders in an atmosphere highly charged with the gas, for instance in the vicinity of a manure pit, as they will then avidly take up the carbon dioxide abundantly liberated from the rotting manure. Similar acceleration will take place if the boards carrying the cylinders are placed in a stable, or in a room where wash for making spirits is fermenting, because large quantities of carbon dioxide are liberated in both places. Working the caustic mass by hand is accompanied by so many inconveniences that it seems highly desirable to employ some mechanical moulding device which will render contact with the wet lime entirely superfluous. It may be pointed out that such a device can also be advantageously used for moulding all earth colours in paste or pulp form, and in particular for shaping ferric oxide colours into rods or small cylinders. [Illustration: FIG. 26.] Such a machine (Fig. 26) is composed of a rectangular box with semi-cylindrical bottom, a detachable shaft carrying a sheet-metal worm being arranged in the box so that the worm is in contact with the rounded bottom and is continued into the cylindrical extension of the box. This extension terminates in a hollow cone, to the mouth of which nozzles of varying aperture (square, rectangular or round) can be attached. A knife, operated by hand or mechanical means, enables the extruded soft mass to be cut into convenient lengths, which drop on to a series of easy running rollers in front of the nozzle, and are thereby delivered to an endless-belt conveyor from which they can be transferred to the drying-boards. When the box has been charged with the lime pulp and the worm is rotated, the latter forces the soft mass into the cone and extrudes it through the nozzle, so that, as long as there is any material in the box, it is discharged as a continuous rope, of square, rectangular or cylindrical section, on to the guide-rollers, where it can be cut off into lengths by the knife.