274 AMMONIA AND AMMONIACAL SALTS. 



the fresh must in order to neutralise the tartaric acid 

 of the must. This acid continued to exisi If now, 

 acetic or any other organic acid should be formed in 

 the vacuum, then as much as at least - 05 grammes 

 ammonia more might be formed by the decompo- 

 sition of ferment, so that the liquid after fermentation 

 would have a less acid reaction than before it was 

 tested. 



Hence from De Saussure's test we must not con- 

 clude that no ammonia is formed during fermenta- 

 tion ; on the contrary, we have seen that it really is 

 produced (p. 67). But as phosphoric acid and mag- 

 nesia exist in grape-juice, the ammonia immediately 

 after its formation is separated out of the fermenting 

 juice as phosphate of ammonia and magnesia. 



