Copy 1

Practical pharmacy: the arrangements, apparatus, and manipulations, of the pharmaceutical shop and laboratory / By Francis [sic] Mohr ... and Theophilus Redwood.

  • Mohr, Francis.
Date:
1849
Catalogue details

Licence: Public Domain Mark

Credit: Practical pharmacy: the arrangements, apparatus, and manipulations, of the pharmaceutical shop and laboratory / By Francis [sic] Mohr ... and Theophilus Redwood. Source: Wellcome Collection.

    85/424 (page 73)
    originally made as a model of a sugar-pan, and is adapted for working about fifteen gallons of liquor at a time. The drawing, however, differs in some respects from the arrangements now generally adopted by the sugar-refiners. The neck (F) is now usually made much shorter and thicker than the drawing repre- sents, and the perforated funnel (1) is dispensed with, the steam itself being pumped into a cistern of water, where it is condensed. Tt would also be desirable to have the steam-chamber (B) much more capacious than it is here represented. The liquid to be inspissated is put into the pan at E, and the cap fitted on. The steam is now admitted into the steam-chamber, and the air exhausted from the interior of the apparatus by means of the pump. <A vacuum being produced, active ebullition will take place when the temperature rises to about 120° Fahr. The vapour passes up the neck (F) and through the descending pipe into the cylinder L. A jet of cold water is now allowed to run at J, and is dispersed in a shower by means of the perforated funnel (1), assisting to condense the steam in its passage into L, from whence it is removed, together with the condensed steam and any air remaining in the apparatus, by means of the pump. The pumping is continued until the completion of the process, and thus a pretty complete vacuum is maintained, and a rapid evaporation ensured. As the loss of some of the contents of the pan may arise from their boiling up through the neck (F), and being carried off by the pump, a glass tube (G) is made to communicate between the pan and the upper part of the neek, so that when the liquid is seen to rise in this tube, the pumping is immediately stopped, and, if necessary, air is admitted into the pan by the stop-cock d, which effectually suppresses the ebullition. No more water should be admitted through the perforated funnel (1) than is sufficient, with the external application of cold water to the cylinder, for the con- densation of the steam. This is ascertained from the temperature of the descending steam-pipe and the upper part of the cylinder. The admission of too much water would tend to destroy the vacuum, by supplying air to the interior of the apparatus. The steam used for heating the pan ought not to be under a pres- sure of more than one or two pounds to the inch, and there should be a plentiful supply of it. The amount of heat carried off during evaporation is precisely the same in this process as it would be if conducted under the pressure of the atmosphere at a much higher temperature, for at whatever temperature the vapour of water