connected with the Boiling of Liquids. 93 



The first arrangement was to boil distilled water in a flask 

 briskly for some time in order to get rid of most of the air. A 

 portion of this water was put into a test-tube dipping in an in- 

 clined position into a bath of oil in a copper bowl. A thermo- 

 meter was placed in the water in the tube, and a second ther- 

 mometer in the oil-bath. The tube and the inserted thermo- 

 meter had been previously cleaned by means of nitric acid, 

 potash solution, and copious rinsing in water. 



Experiment 1. — Test-tube about § inch in diameter inside. 

 Barometer 30*275 inches. 



Bath 225 Water 210. First bubble of steam. 



240 214. Boiling in jerks. 



260 218. Boiling. 



280 218. 



Experiment 2. — Same tube. Barometer 30*245 inches. 



Bath 225 Water 210. First bubble of steam. 

 240 214. Boiling violently. 



290 216. Boiling briskly. 



Experiment 3. — Tube about 1| inch in diameter. Barometer 

 30*245. The thermometer-bulb deep in the water, and nearly 

 at the bottom of tube. 



Bath 240 Water 210. First bubble of steam. 

 270 214. Boiling briskly ; it 



280 then remained quiet during three 



minutes, rising to 

 290 220. Quiet during four minutes. 



310 222-224. Then a burst of steam, and tempe- 



rature fell to 218°. 

 310 224. Burst of steam, and temperature fell to 



220°. 

 310 224. Burst of steam, and temperature fell to 



214°, and continued to boil. 



Experiment 4. — Same tube. Barometer the same. Ther- 

 mometer-bulb near the surface of the water. 



Bath 2/0 Water 214. First bubble of steam, then quiet up to 

 216. A few bubbles. 



218. Burst of vapour. 



270 216. Boiling steaddy for some minutes, then 



quiet. 

 285 222. Burst of vapour. 



219. Quiet, with evaporation from surface 



without bubbles until the bulb of the 

 thermometer became uncovered. 



The foregoing results agree with my own experience. The 

 water becomes superheated a few degrees, then relieves the ten- 

 sion by a burst of vapour, and the temperature falls; there is 

 also rapid but quiet evaporation from the surface, which also 

 serves to keep down the temperature. 



