APPENDIX. 



INTRODUCTION TO THE ANALYSES. 



THE method formerly employed to exhibit the differ- 

 ences in composition of different substances, that, namely, 

 of giving the proportions of the various elements in 100 

 parts, has been long abandoned by chemists ; because it 

 affords no insight into the relations which exist between 

 two or more compounds. In order to give some proofs 

 of this statement, we shall here state, in that form, the 

 composition of aldehyde and acetic acid, of oil of bitter 

 almonds and benzoic acid. 



Oil of 



Now aldehyde is converted into acetic acid, and oil of 

 bitter almonds into benzoic acid, simply by the addition 

 of oxygen, without any change in regard to the other 

 elements. This important relation cannot be traced in 

 the mere numerical results of analysis as above given ; 

 but if the composition of the related compounds be ex- 

 pressed in formulae, according to equivalents, the con- 



