44 VINEGAR, CIDER, AND FRUIT-WINES. 



radical, for instance by methyl CH 3 or ethyl C 2 H 3 , the so-called 



compound ethers are formed. 



CH 3 \ n C 2 H 5 \ 



C 2 H 5 Oj C 2 H 3 0/ C 



Acetic acid-methyl ether. Acetic acid ethyl ether. 



If a bivalent metal or compound radical yields a neutral com- 

 bination with awtic acid, the substituted hydrogen in two mole- 

 cules of acetic acid must evidently be replaced by this bivalent 

 metal, for instance : 



Ca \ 



2(C a H/>) j J * 



Neutral calcium acetate. 



Theoretical Yields of Acetic Acid. 



In industries based upon chemical processes a distinction is 

 made between the theoretical and practical yields. 



By theoretical yield is understood the quantity of the body 

 to be manufactured which would result if no losses of substance 

 were connected with the chemical process ; the practical yield, 

 on the other hand, is that in Avhich such losses are taken into 

 account, the average being ascertained by long-continued compari- 

 son of daily yields. The closer the practical yield approaches 

 the theoretical, the more suitable the method pursued in the fabri- 

 cation evidently is, and thus the manufacturer, who has a clear idea 

 of the theoretical yield, can readily judge of the value of his 

 method by comparing it with the practical yield attained. 



Now suppose no loss of substance (by evaporation or forma- 

 tion of other combinations) occurs in the conversion of alcohol 

 into acetic acid, it can be readily calculated from the composition 

 of the two bodies how many parts by weight of acetic acid can 

 be formed from a determined number of parts by weight of 

 alcohol. 



Alcohol has the composition C 2 H 8 O, or an atomic weight of 46, 

 because : 



C 9 ...... 24 



H n = 6 



O = 16 



Makes 46 



