SPONTANEOUS RISE OF HOT LIE IN A PUMP. 1 QS 



the level of the spout. I am greatly disposed to think the 

 condition that the heated lie must all pass between the 

 two hot metallic bodies, the lower edge of the suction-pipe, and 

 the bottom of the boiler, is of great consequence to the whole 

 effect. 



In order to bring the subject in some measure to the test of Experiment. 

 . T . 1 . u , , 1 • , 1 J Water boiled 



experiment, I took a tubular glass vessel, ten mches long, and j,^ ^^ vessel, ia 



one inch internal diameter, having a small enlargement, or foot which an up- 

 to stand upon, as a chemical measure. By a smart stroke with [^^'^ JaT'pIsi- 

 the end of a pointed file, I drove the bottom in, by making a ced, stood 

 large hole in the middle without breaking the other parts. In ^^^^^^ '° * 

 this state it was capable of standing on its bottom as before. A. 

 tin vessel with a fiat bottom was then filled to the depth of three 

 inches with water, and the glass vessel being set upright in the 

 water, the whole was placed on the fire. As soon as the liquid 

 began to boil, the bubbles were most plentiful in the, tube, and 

 the water stood at rather less than three quarters of an incja 

 higher in the tube than in the exterior vessel. When the boil- Particular cir- 

 ing was very rapid, the difference was rather less, and when the th^pxp""* " 

 tube was raised a little from touching the bottom, the diffe- ment. 

 rence ceased. Upon taking the tube out, and letting it cool, 

 and then setting it as before in the boiling water, the difference 

 or rise did not take place, nor was any boiling seen within the 

 tube till after the lapse of about half a minute j and upon in- 

 verting the tube, so that its mouth touched the bottom of the 

 tin vessel, and the foot was uppermost, the water within it did 

 tiot stand so high, nor boil so fast, as when the contrary position 

 was adopted. And lastly, the difference appeared rather more 

 considerable when the boiling was moderate, than when the 

 whole mass of the fluid was full of steam-bubbles by rapid 

 ebullition. Inferences 



Though the preceding experiment is not so apposite and The higher 

 1 • '. ■ u.u u 1 u • ^ J .1 station in level 



conclusive as it might have been made, by using a greater depth ^f jj^g ^ater 



of a saline fluid, and allowing a side aperture for the same to in the tube 

 n ^ ■ , ^ -^ ^ i I -.u was occasion- 



flow out as in the pump i yet it appears to me to show with ^^ j, ^^^^^ 



sufficient precision, 1 . That the column of fluid in the tube was produced most 



of less specific gravity, from the greater admixture of steam- ^J^^^ theVw- 



bubbles, than a like column of the exterior heated fluid, and er part of the 



therefore stood higher. 2. That the excessive quantity of steam J^'^'^^f "^g v^s^ 



was produced from the thin film of water between the foot of sel. 



Vol. XXXIII, No. 153.--N0VEMBSR, 1812. O the 



