24 THE CHANGE OF VOLUME IN THE TWO 



in order to keep in equilibrium the lead drop at d, 

 rather more water is added than exactly suffices 

 to bring the liquids to the same level in both 

 tubes. 



The liquid in a increases in volume, and the 

 height to which it rises may be read off by means 

 of any division into equal parts by measure ; the 

 level of the liquid in b sinks in an equal ratio. If 

 we keep the liquid in b, by the addition of fresh 

 water, at the original level, and if we ascertain the 

 weight of the added water, by pouring it out of a 

 dropping bottle, and determining the loss of weight 

 in the dropping bottle, we learn at the same time 

 the weight and the volume of the water which 

 has risen from c into a. This apparatus admits, of 

 course, of a number of variations and improve- 

 ments. I have employed it to determine the rela- 

 tion between brine and water, under the circum- 

 stances just described. It appeared, among other 

 things, that when the tube a is filled with saturated 

 solution of sea salt, the volume of the liquid in- 

 creased by nearly one half; that is, 200 volumes 

 of such a solution increased to 300. These deter- 

 minations are, however, not the object of the pre- 

 sent investigation, and therefore I pass them over 

 entirely. 



