APPENDIX. 439 



APPENDIX, 



IN this Appendix are included formulae descriptive of chem- 

 ical reactions of the text, and other matter no less important, 

 whose introduction into the text would have interfered in a 

 measure with the plan of the work. 



The formulae constitute a precise statement, in the lan- 

 guage of the symbolical nomenclature, of the reactions al- 

 ready described in more general terms. It is not to be 

 understood from the formulae that the materials concerned 

 in any process must always be brought together in the pre- 

 cise proportions indicated in the first member of the equation. 

 One or the other may be in excess ; if so, the excess is null, and 

 not considered in the formula. The latter regards and indi- 

 cates only the relative quantities which are actually concerned 

 in each reaction the first member having reference to the 

 materials employed, and the latter to the products. 



Interpreted according to the atomic theory, each formula 

 gives on the one side of the equation, the nature and rela- 

 tive number of the atoms or molecules which take part in 

 any reaction, and on the other, the nature and relative num- 

 ber of those which result. 



The student will do well, as an occasional exercise, to cal- 

 culate from the formulae the relative quantities of materi- 

 als required in a reaction, and of products resulting from it 

 in pounds and ounces. A T in the tables stand respectively 

 for acetic and tartaric acids. 



