CHAPTER VIII. 



Hydrometers or Saccharometers, and their Use. 



THE sugar in cane-juice being sub'ject to very 

 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 efl'ect 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. 



