INTRODUCTION. 9 



may be supplied by the knowledge chemistry 

 gives us 01 other substances which may con- 

 tain it. 



This is, perhaps, the most important fea- 

 ture of chemistry as applied to agriculture, but 

 still in its subordinate functions of enabling us 

 to discover the elements and consequent value 

 of refuse matters, it may be regarded as a valua- 

 ble accessory to the farmer, to say nothing 

 of its importance in pointing out remedies 

 for such minor matters as the prevention of 

 smut in corn, by the use of sulphate of copper — 

 the preservation of plants by the galvanic bat- 

 tery — the preservation of timber by the pro- 

 cess of kyanising, &c. all of which are of con- 

 siderable value in their various applications. 



To these facts may be added instances, 

 where a knowledge of chemistry has created a 

 new branch of trade entirely for the agricultu- 

 rist, when if such knowledge had not existed, 

 serious consequences would have ensued. 

 The manufactures of sugar and saltpetre in 

 France during the revolutionary war are the 

 instances alluded to, and the circumstances 

 which led to tlieir introduction there are briefly 

 these:—-' That vvlien France had lost all her 

 colonies and when her coasts were held in a 

 state of strict blockade by the fleets of England, 

 the supply of sugar necessarily failed. It was 

 then that the chemists to whom the Govern- 

 ment applied in their emergency, pointed out 

 that sugar might be obtained from the grape 

 and subsequently from the beet root, and to 



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