92 Chemistry. [Lecture 27. 



If we throw in lead, the copper will be deposited 

 the lead by iron, &c. 



Another remarkable phenomenon is, that 

 some bodies are less in bulk, others greater, when 

 mixed. Silver is lighter than quicksilver; yet 

 quicksilver and silver united form a compound 

 heavier than quicksilver of equal bulk. 



Water is not increased in bulk by the addition 

 of a small quantity of salt ; if the quantity of salt 

 is, however, increased, the liquor will be in- 

 creased, but not in the proportion of the aggre- 

 gate weight of the two. 



M. Reaumur made the following experiment : 

 a vessel was half filled with water, spirit of wine 

 was then gently poured into it, till the mixture 

 rose half way to the neck of the vessel. The 

 bottle was then shaken, and a little heat was 

 produced; the liquor consequently rose; but 

 when the heat was gone off, the mixture took up 

 less room than it did before the two fluids were 

 united by shaking. 



I shall now consider the several theories and 

 explications of the effects of mixture. From the 

 first sera of chemistry till the time of Lord Veru- 

 lam, we had no intelligible theory; they seldom 

 went further than to explain one term by another. 

 Thus finding that the alkalies effervesced with 

 acids, whenever they found a substance that 

 effervesced with an acid, the philosophers of the 

 day defined it to be of an alkaline nature. 



Most of the chemical phenomena are difficult 



