338 PHYSIOLOGY AT THE FARM. 



means so suitable for a condiment as the vinegar obtained by 

 fermentation. 



Vinegar. Common vinegar is malt vinegar, made by sub- 

 jecting an infusion of malt, or a mixture of malt and raw 

 barley, to the acetous fermentation. It contains a minute 

 quantity of sulphuric acid. It owes part of its peculiar taste 

 and odour to the presence of acetic ether. 



Four malt vinegars are known in commerce, of different 

 degrees of strength. They are numbered 18, 20, 22, and 24. 

 The vinegar marked as 24 is called proof vinegar, and is the 

 strongest that is made. It is rather too strong for use at the 

 table, but serves for pickling and preserving meat, fish, and 

 game ; it is therefore known as the strongest pickling vinegar. 

 The vinegar marked 22 is often called best pickling vinegar, 

 being adapted for pickling most vegetables. It is that best 

 suited for the table. 



Composition of malt vinegar : 



Acetic acid. 



Acetic ether. 



Colouring matter. 



Peculiar mucilaginous matter. 



Alcohol (a small portion). 



Sulphuric acid (l-1000th part). 



Water. 



Vinegar-makers are permitted by the excise laws to add 

 the above proportion of sulphuric acid to malt vinegar. 



French vinegar, called also wine vinegar, is made in France 

 from wines of inferior quality. It is either white-wine vine- 

 gar or red-wine vinegar. The white-wine vinegar is com- 

 monly preferred, as it keeps better. The composition of wine 

 vinegar differs but little from that of malt vinegar. Bitartrate 

 and sulphate of potassa are present in it in small proportion. 

 The wine vinegar is distinguished from malt vinegar by the 

 purplish precipitate given by ammonia added to wine vinegar. 



