ous acid, depending to some extent upon the amount of sulphur used 

 in fumigating. 



When sulphurous acid is used as a preservative for food products 

 after the manufacture has been completed, it is usually employed in 

 the form of bisulphite of lime or some similar preparation. Sulphur- 

 ous acid has the property of uniting with certain organic radicals, such 

 as aldehydes and some sugars, to form compounds which are more or 

 less stable, and in this form it is known as combined sulphurous acid. 

 When it exists in the form of an absorbed gas or in combination with 

 an ordinary metallic base, such as soda, potash, or lime, it is said to 

 be in a free state. Combined sulphurous acid is set free from the or- 

 ganic combination by treatment with an acid with the aid of heat or 

 with a dilute alkali in the cold. 



In the accompanying report the effects of the combined sulphurous 

 acid are not to be considered, except in so far as the combination 

 takes place with the foods with which the sulphurous acid may be 

 mixed after entering the stomach. The purpose of the investigation 

 is, therefore, to determine practically the effect of free sulphurous 

 acid that is, sulphurous acid in a gaseous state absorbed by water or 

 united with a base rather than the effects of combined sulphurous 

 acid. In no case has any question been considered in these investi- 

 gations relating to the food value of the organic sulphur existing in 

 proteids and other foods. 



i It is true that probably in the process of digestion complete saponi- 

 fication of the combined sulphur compounds takes place, so that 

 finally they appear in the small intestines in a free state that is, as 

 sulphurous acid or sulphites and are then oxidized to sulphuric acid, 

 as is the free sulphurous acid, during the metabolic processes. 



Practically, in the technical use of sulphurous acid in the manu- 

 facture of food products only the fumes of burning sulphur are 

 employed. Desiccated fruits, pared or unpared, are subjected, after 

 the removal of the pit or core, to the fumes of burning sulphur in 

 what is known as a " sulphur box." In the manufacture of wines 

 a piece of so-called " sulphur candle " that is, a piece of cloth which 

 has been dipped in melted sulphur is burned. This candle is 

 attached to a wire, ignited, placed in the barrel, the bung inserted, 

 and the candle allowed to burn until the whole of the sulphur is con- 

 sumed. Previous to the sulphuring it is the custom to thoroughly 

 wash the barrel so that the interior thereof at the time of sulphuring 

 is moist. The moist surface of the wood absorbs the sulphurous acid 

 more freely than does the dry wood. The ostensible object of the 

 sulphuring is to keep the barrels sweet; in other words, to destroy 

 any yeasts or other ferments which may adhere to the surface of the 



[Cir. 37] 



