178 Chemistry. [Lecture 30. 



acid, as they dissolve in proportion to the lime 

 they contain. 



The sulphuric acid attracts calcareous earths 

 with great impetuosity. When it is added to 

 chalk, we shall find the earth not dissolved, but 

 settling by degrees into a sediment more bulky 

 than the chalk itself. The reason of this ap- 

 pearance is, that the chalk, though united with 

 the acid, has very little solubility in water, one 

 pound weight of water being necessary to dis- 

 solve a few grains. When the chalk settles to 

 the bottom, the bulk is increased by the addition 

 of the sulphuric acid. The compound thus 

 formed is sulphat of lime; formerly, and even 

 now, vulgarly known by the names of gypsum, 

 selenite, or plaster of Paris. 



The other mineral acids unite with this earth 

 with effervescence, and dissolve it into a trans- 

 parent fluid, and the compounds are easily solu- 

 ble in water. 



Acetous acid forms with lime an exceedingly 

 soluble salt. Many of the other vegetable acids 

 readily unite with it, some of the resulting salts 

 being soluble, others not. The oxalic acid has a 

 peculiarly strong attraction for this earth, seizes 

 it even from the mineral acids, and precipitates 

 with it in an earthy form. Hence this acid is 

 the best test for the presence of lime in solutions, 

 as it will detect the smallest portion. 



We do net find that lime melts in fire, but it 

 is much changed by it ; it becomes more friable 



