66 



'2. COMPOSITION AND DECOMPOSITION OF BODIES. 



We have seen that simple bodies combine to 

 form compound bodies (acids and oxides) and that 

 these latter combine to form other more complex 

 bodies called salts, as carbonate of lime, sucrate of lime. 

 We will see that one of the most important opera- 

 tions in the manufacture of beet root sugar, the 

 purifying and clarifying of the juice, depends on 

 these principles. 



All my readers have observed another pheno- 

 menon, by which two compound bodies in solution 

 in a liquid may act one upon the other, not to com- 

 bine together, but each to take from the other one 

 of its elements and to form new and distinct bodies- 

 This is often done, when an acid is placed in contact 

 with a salt and that the base of this salt has more 

 affinity for the other acid than with which it is in 

 combinaticn. This is every day noticed in the 

 manufacture of gaseous waters. It is known that 

 the distinctive quality of this water is carbonic 

 acid, retained in solution in water. To produce 

 this carbonic acid gas, water is dissolved in tartaric 

 acid and soda or carbonate of soda, tartaric acid has 

 more affinity for soda than carbonic acid, that is to 

 say, it has a greater tendency to unite, to combine 

 with this base. As soon as tartaric acid is found in 

 presence of carbonate of soda in the solution, the 

 latter is decomposed, the tartaric acid drives away 

 the carbonic acid and takes possession of the prin- 

 cipal ingredient, and forms ta>-trate of soda and the 



