30 AGKICULTUEAL CHEMISTRY. 



one of sulphuric acid, 40 ; and 2 H O, two of water, 

 18 ; making 86. If this salt be heated to redness, the 

 water of crystallization is driven off, and 86 lbs. of it 

 become 68 lbs. Sixty-eight pounds of burnt gypsum 

 are of equal value, therefore, with 86 lbs. of ground. 

 The learner, it is presumed, can now go on, and ana- 

 lyze for himself the remaining expressions for salts in 

 Table II., satisfying himself in each case, what are the 

 ingredients of the salt ; whether it contains in its crys- 

 tallized state any water of crystallization ; and, if any, 

 how much. In this way he will learn the composition 

 , of many substances, and be rendering himself familiar 

 with the language of chemistry. 



The nature of these substances will next claim our 

 attention. Occasional applications will be made to 

 agriculture as we pass along; but such application 

 will be reserved mainly for another part of this work. 



COMPOUNDS. 



45. Chloric acid (ClO^, see Table II.) is a violent, 

 powerful acid, having so strong affinity for all com- 

 bustible substances, that it can hardly be preserved with 

 safety. 



46. Sulphuric Acid is a compound of great impor- 

 tance in the arts, and is beginning to be used exten- 

 sively in agriculture. If it contained no water, we 

 should have in 40 pounds of the acid 16 lbs. of sul- 

 phur and 24 lbs. of oxygen ; but as it always contains 

 water, more or less, these ingredients are of course 

 less than 16 and 24 lbs. in 40, but are always in that 



