CHAPTER VIII. 



Hydrometers or Saccharometers, and their Use. 



sugar in cane-juice being subject to very 

 -L great variation, it is convenient to have some 

 means of ascertaining approximately the richness of 

 the juice. This is usually done by means of the hy- 

 drometer, the use of which depends on the following 

 points : When a solid substance, such as sugar, is 

 dissolved in water, the density or specific gravity * 

 of the solution is found to be greater than that of 

 water, and increases in proportion to the quantity 

 of solid substance dissolved ; hence, if the fluid con- 

 tain only one substance in solution, it is easy to 

 ascertain precisely the amount dissolved by merely 

 finding the specific gravity ; but when the fluid con- 

 tains two or more substances, this becomes quite 

 impossible, as both have a similar effect in increas- 

 ing the specific gravity, and it is impossible to say 

 how much of the increase is due to one substance 

 and how much to a second. 



When any body floats in a fluid it sinks until the 

 part submerged displaces exactly the same weight 



* Density or specific gravity is the weight of any substance 

 compared with the weight of an equal volume of water taken as 

 unity. 



