Where, however, a considerable weight must be raised before any steam can escape, as in steam-engine boilers, considerable injury may arise, not only in the boiling of ale worts, but also of porter or stout worts; arising from the following causes.
In the first place, owing to the high pressure of steam, which must necessarily take place before the weight can be raised to allow of its escape, the evaporation of the worts in boiling is so trifling as to prevent the necessary increase of gravity, so as to enable the brewer to turn the proper quantity of liquor over his malt in the mash-tun, for producing the best extracts, particularly for beers of high gravities.
2. The weight to be raised before any escape of steam can take place, and the consequent high pressure, must necessarily raise the temperature of the worts in the copper far above the boiling point. This must, therefore, to a certain extent, alter the component parts of the worts, by charring or carbonising them. That this effect is produced, is sufficiently proved, not only by the brick-red colour of the worts when coming out of the copper, (although brewed from the palest malt,) but also by the beer, which can never have that fine pale or amber colour, so highly desirable for all sorts of ale.
3. The above-mentioned high temperature must also be to a certain extent injurious to brown beer,
