AUGUST

See also:

• FRIEDRICH, JOHANN (1836— )

FRIEDRICH

See also:

• AUGUST FRIEDRICH GFRORER (1803–1861)

GFRORER (1803–1861)  , German historian, was born at Calw, Wurttemberg, on the 5th of March ' So written, with a medial mem (re) instead of the final (o) . to account for the frequent and periodical production of the necessary heat ; but he has the credit of hitting on what is certainly the proximate cause—the sudden evolution of steam . By Bunsen's theory the whole difficulty is solved, as is beautifully demonstrated by the artificial geyser designed by J . H . J . Muller of Freiburg (fig . 2) . If the tube ab be filled with water and heated at two points, first at a and then at b, the following succession of changes is produced . The water at a beginning to boil, the superincumbent column is consequently raised, and the stratum of water which was on the point of boiling at b being raised to d is there subjected to a diminished pressure; a sudden evolution of steam accordingly takes place at d, and the superincumbent water is violently ejected . Received in the basin c, the air-cooled water sinks back into the tube, and the temperature of the whole column is consequently lowered; but the under strata of water are naturally those which are least affected by the cooling process; the boiling begins again at a, and the same succession of events is the result (see R . Bunsen, " Physikalische Beobachtungen fiber die hauptsachlichsten Geisire Islands," Pogg . Ann., 1847, vol .

72; and Muller, " Uber Bunsen's Geysertheorie," ibid., 185o, vol . 79) . The

principal difference between the artificial and the natural geyser-tube is that in the latter the effect is not necessarily produced by two distinct sources of heat like the two fires of the experimental apparatus, but by the continual influx of heat from the bottom of the shaft, and the differences between the boiling-points of 186° 225° the different parts of the column owing to 230° 241° the different pressures of the superincum- ° bent mass . This may be thus illustrated: C 249 AB is the column of water; on the right 255° side the figures represent approximately the boiling-points (Fahr.) calculated according to the ordinary laws, and the figures on the left the actual temperature of the same places . Both gradually increase as we descend, but the relation between the two is very different at different heights . At the top the water is still 39° from its boiling-point, and even at the bottom it is 19°; but at D the deficiency is only 4° . If, then, the-stratum at D be suddenly lifted as high as C, It will be 2° above the boiling-point there, and will consequently expend those 2° in the formation of steam .