AGRICULTURAL CHEMISTRY. 27 



with another element ; those ending in afe, are in all 

 cases the result of an acid combined with an oxide^ or 

 base. Thus, if you combine sulphur (an element) with 

 iron (another elem£nt\ you have a sulphuret of iron ; 

 but if you first combine sulphur and iron with oxygen, 

 to form sulphuric acid and oxide of iron, and then 

 combine these last with each other, you have a sulphate 

 of iron. In other words, sulphur, phosphorus, and 

 carbon, combined with any of the elements below 

 them in Table I., form sulphwrefe, phosphwrefo, and car- 

 hurets; but if sulphuric acid, phosphoric acid, and 

 carbonic acid combine with any of the bases below 

 them in the second column of that table, they form 

 sulphates, phosphates, and carbonates; and if twice 

 the usual quantity of these acids are thus combined, 

 they form Z^isulphates, Z^iphosphates, and 5^carbonates, 

 as before explained. 



42. If the learner is desirous of making real pro- 

 gress, he must master the principles laid down in the 

 few preceding pages. This done thoroughly, he will 

 find little difficulty. Let him turn back and review 

 the brief description of the fifteen elements before 

 given. Of these he needs to have as distinct, definite 

 an idea as possible. Let him then look at Table I., and 

 question himself on each of the binary compounds. 

 On the first, he may inquire of what is chloric acid 

 composed ? The figures will point him to the two ele- 

 ments, and the symbol will show him in what pro- 

 portion those elements combine to form it. The 01 

 shows him that chlorine is one of its elements, and the 

 shows him that oxygen is tba other. The atom of 



