CBITICAL NOTICES OP NEW PUBLICATIONS. 321 



examined by experiment. The Committee of the Franklin Institute 

 made this examination under two heads ; 1st. As to the fact, whether 

 or not high steam may be rapidly produced by water thrown into a 

 red hot boiler ; 2nd. The circumstances modifying the production of 

 steam in such cases. 



The experimental boiler being heated to redness, different quanti- 

 ties of water were thrown into it, producing various pressures of 

 steam from three to twelve atmospheres.* 



We may here notice an opinion, formerly advocated by a practical 

 engineer, that when water is thrown into a heated vessel containing 

 steam surchai-ged with heat, it is the surcharged steam, and not 

 the heated metal, which supplies the heat to the water to flash it into 

 steam. This hypothesis was submitted to direct experiment by the 

 Committee of the Franklin Institute. Steam having been produced 

 within a boiler, was surcharged with heat by applying a charcoal fire 

 to the top of the boiler. In this way the temperature of the steam 

 was raised, in one experiment, to 533° F., at which it had an elastici- 

 ty of 6.8 atmospheres, while steam of the full density, corresponding 

 to that temperature, would (by calculation) have had a pressure of 

 more than sixty atmospheres. Water being thrown into steam thus 

 surcharged, invariably diminished its elasticity : thus showing that the 

 theory which has so often been applied to refute the error of this 

 hypothesis has in reality been rightly applied. Much difficulty ap- 

 pears to have been encountered in these experiments by an attempt to 

 make them without more expense than the intrinsic worth of the 

 matter to be determined warranted.f 



* In this last case the steam was produced in " a time not exceeding one 

 or two minutes at the most," bursting one of the glass plates in the head of 

 the experimental boiler, and which served to give a view of its interior — 

 Seven experiments are given, in which water was thrown into the boiler 

 when the metal was red hot. Our ingenuous critic remarks that "the blow- 

 ing out of one of the little windows of the boiler put an end to it [the series 

 of experiments] when it was becoming interesting" — we should say, when 

 completed. 



•|- In reviewing these experiments, the Magazine of Popular Science says, 

 " It is scarcely credible, but the temperature of the water in the boiler beneath 

 the steam was not thought sufficiently important to be noted." To shew that 

 the reviewer could not have read the article under review, we make from it the 

 extracts in regard to the very point which he asserts (implies) was neglected. 

 " To measure the temperature thus acquired by the steam, as well as that of 

 the water below it., thermometers were placed in the iron tubes already de- 

 scribed ; the mercury was removed from the tubes, except enough to cover 

 the bulbs of the thermometers, so that the temperatures shown by them 

 might be, as nearly as possible, that of the steam by which the shorter tube 

 was surrounded, and of the water into which the longer tube dipped" — Report j 

 part i., p. 19. •' The temperature of the thermometers in the water and 

 steam were noticed both before and after the injection." — Report, part i., p. 

 20. " In the last day of trial the heat of the top of the boiler was so great 

 and so long sustained that the thermometer in the water became, for reasons 

 which will be stated, comparatively useless as an indicator of the tempera- 

 ture of the water." — Report^ p. 20. It appears clearly, from this article, 

 which we have read, that, not prejudging the results of experiment, the Com- 

 VOL VI. NO. XX. SS 



