﻿322 Intelligence and Miscellaneous Articles. 



Then by uniting the two values of V, we have 

 c^-t and — ccdcv=y 3 



qT\ —— /% *f n-rt ri /v»>t7/vt— *»"- 



7 4. 



Then by integrating, k~ x2= 4 > anc * ex Acting the root, 



(£)*•=* 



the well-known equation of a parabola. — Q. E. I. 



Samuel Sharpe. 

 32 Highbury Place, 

 March 20, 1871. 



IV 



A NEW EXPERIMENT,, AND SOME REMARKS ON THE THEORY OF 

 LEIDENFROST'S PHENOMENON. BY E. BUDDE. 



"Leidenfrost's drop is suspended when the vapour below it can 

 support the pressure of the atmosphere plus the weight of the drop, 

 If the former be removed, a far smaller tension must be sufficient to 

 produce the phenomenon." This conclusion incited me to make the 

 experiment of producing, by means of the air-pump, a Leidenfrost's 

 drop with water upon a support at less than 100° C. With this view 

 the following apparatus was constructed. Upon a copper dish (a) 

 a glass bell-jar (g) about 8 

 centims. in diameter was ce- 

 mented. Through a cork at 

 the top of the bell-jar passed 

 two glass tubes (7 and m) ; 

 the end of one of these (/), 

 bent at right angles, just pro- 

 jected below the cork, while 

 the other end was connected 

 with the air-pump by means 

 of an india-rubber tube. One 

 end of the second tube (m) 

 reached inside the bell-jar to 

 near the dish (a); the other 

 end, outside the cork, was bent 

 somewhat in the shape of the 

 letter N and was sealed. This 

 bent part, which may be called 

 N, was filled with water, of 

 which it held about one third of a gramme. 



The dish was placed in a water-bath, which kept it at a tempera- 

 ture of 80° to 100°. Suppose now the apparatus evacuated. By 

 adequate exhaustion the water in N will liberate bubbles of air and 

 vapour, which will partially collect in the upper closed part, and cause 

 the water to flow down through the other end of the tube. This 

 will fall either quite boiling, or very nearly so, on the dish, which is 



