PREFACE. Vli 



;i man consume L Ib. of butter, he could utilize one-fifth of 6,450 tons 

 in raising them one foot from the ground; or, supposing he lift a 25 Ib. 

 weight to the height of 1 foot, he might repeat it 116,000 times before 

 the force was all expended. 



Lastly, for the reader to carry in his mind some sort of standard, 

 he may remember that Peas and Beans and other seeds of leguminous 

 plants have the greatest amount of nitrogenous albuminoids, the Lentil 

 having most of all, or 25 per cent. ; whereas Potatos may be taken to 

 illustrate a standard for carbohydrates viz. 18 per cent. the nitro- 

 genous albuminoids being only 1^ per cent. 



