10 INTRODUCTION. 



such an extent was this manufacture carried, 

 that France, until a recent period (1834,) was 

 supplied exclusively by her home manufac- 

 ture." 



Again, the same causes prevented France 

 from receiving a supply of saltpetre for the 

 manufacture of gunpowder, but the same 

 energy which induced the home manufacture 

 of sugar, found a means of making saltpetre 

 from the refuse matter of farm-yards; and so 

 great was the supply from this source that it 

 enabled France to maintain her gigantic strug- 

 gle for the subjugation of Europe, for a pro- 

 tracted period, with unimpaired vigour, when, 

 had not such means been discovered, she must 

 have submitted to what she would have con- 

 sidered a disgraceful peace. 



Again, chemistry enables us at once to test 

 the real value of any given substance, without 

 the uncertainty and loss of time attendant on 

 a trial ; and when it is considered how much 

 time must have been lost, how unsatisfactory 

 the results must repeatedly have been, when 

 no such knowledge existed whereby to certify 

 the progress of discovery ; the value of this 

 science may in some measure be estimated. 



Other instances might be adduced, if neces- 

 sary, but enough has been said to show the 

 intimate connexion which ought to exist be- 

 tween chemistry and agriculture. Indeed, 

 the knowledge of the one is essential to suc- 

 cess in the other ; and it is hoped that the 

 spirit of inquiry which now exists universally, 



