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EXPLANATION OF THE PLATES.

5. Cast-iron pipes, conveying the condensed water throughthe syphon into the hot-water cistern 7, whence it is occa-sionally forced into the boiler by the process 8.

6. Small vessels constructed similarly to those marked 3, fordistillation in glass retorts.

b. The chimney of the boiler which passes under the floor ofthe laboratory ; e d, valve Boxes.Fig. 2. Represents a section of the boiler: 1. the steam boiler;2. the mam steam-pipe ; c, the safety-valve ; d, waste-pipe;k, registers of the steam-cocks ; 3. evaporating boilers;5. the condensed water-pipe.

3. Section of the steam-boiler, showing the connexion of thesteam and condensing pipes, with four smaller evaporatingpans.

4. iv and v, Are top and side views of a valve-box, atta-chedto the extremity of the main steam-pipe at e, fig. 1. inorder to carry off any water produced by the condensationof the steam in the main without suffering steam to escape.2. Termination of the steam main; g, the cork float,which when raised by water in the box, opens the cock, h,and suffering it to run off, the float subsides and closes thecock ; ?', fig. 5. is a cock by which the air is suffered occa-sionally to escape from the steam-pipes.

Similar boxes are attached to several of the condensing pipes ofthe other vessels.

Plate 7. '

The annexed plate represents an elevation of one side of theStxam Laboratory; the ground plan of which was given in thelast plate; the figures and letters of reference are the same asbefore.Fig. 2. The main steam-pipe.

3. An evaporating boiler.

4. The stills. 5. The condensed water-pipe. &, The steam-cocks with their registers.

a, The worm-tubs.n, n, Pipes carrying off hot water from the surface of the worm-tubs, the place of which is supplied by cold water enter-ing below, from the back I.

FINIS.

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