1 72 CHEMISTR V FOR A GRIC UL TURA L STUDENTS 



is again produced. It is the manifestations of this force of 

 chemical attraction between elements and groups of elements 

 with which the science of chemistry is concerned. 



In the course now completed, the student has dealt with 

 the composition of air and water, the minerals of the earth's 

 crust, and the products of animal and vegetable life, as far as 

 was necessary to enable him to understand the principal laws 

 that govern the composition of matter, and the properties of 

 the substances with which he would be most intimately con- 

 nected on the farm. He has become accustomed to regard 

 change, whether in the animal, vegetable, or mineral kingdoms, 

 as involving chemical changes, similar in kind to the examples 

 which have been dealt with in the laboratory ; and which can 

 be controlled and modified, provided they are understood. 

 Not only, therefore, should the knowledge acquired enable 

 him to understand the processes of the farm, but he should 

 now view them from an intelligent standpoint, and hence be 

 better prepared to attack the problems presented for solution 

 in all agricultural pursuits. 



QUESTIONS AND PROBLEMS FOR REVISION AND 

 EXAMINATION. 



The Carbohydrates. 



What is a "carbohydrate"? Name some. How do carbohydrates 

 behave when they are heated ? Explain the action of concentrated 

 sulphuric acid on sugar. 



Name the principal sources of starch, and state how it is prepared. 

 How may starches be distinguished from each other, and by what 

 chemical test can starch be identified ? 



Describe the action of dilute sulphuric acid on starch mucilage, and 

 state what is the behaviour of the liquid at each stage to solution 

 of iodine and to alkaline copper sulphate solution. What sub- 

 stances, other than sulphuric acid, are able to bring about the 

 same series of changes .'* 



