o 



4. Sulphurous acid and sulphites. 



5. Benzoic acid or benzoates. 



6. Fluorides. 



The boron preservatives are apparently the most commonly used, and 

 are preparations of boric acid and borax, with or without admixture of 

 other preservative ingredients, such as salt, saltpetre, sugar, sodium 

 carbonate, etc. They are used largely in milk, cream, and butter for 

 preserving meat food generally, and to a smaller extent in beverages. 



Formalin is a 40 per cent, solution of formaldehyde. As a preser- 

 vative it is used chiefly in milk. In concentrated solutions it has a strong 

 irritant odor, but when added to milk in quantities sufficient to retard fer- 

 mentative action, it cannot be detected by taste or smell. The addition 

 of formalin to milk is undoubtedly objectionable, as it interferes with 

 digestion. 



Salicylic, sulphurous, and benzoic acids and the fluorides are appar- 

 ently used to some extent in dairy products, but more commonly in meat, 

 fruit, vegetable preparations, beverages, etc. Salicylic acid is a 

 powerful preservative, but it has a sufficiently characteristic taste to pre- 

 vent it being used except in very minute quantities as a butter preser- 

 vative. 



Nearly all the preservatives now on the market are advertised as be- 

 ing "entirely wholesome," or that "its ingredients are all as healthful as 

 salt," "capable of keeping the various articles of food perfectly sweet and 

 fresh for any length of time, without the use of ice," etc. They are sold 

 under a great number of fancy names, which, as a rule, give no clue to 

 their real nature. On account of the perishable nature of foods, it is 

 obvious that a substance having the properties claimed for the various 

 commercial food preservatives would be of incalculable value. At the 

 same time, we must recognize the fact that authorities differ as to the 

 correctness of these claims, even for the boron compounds, which are 

 possibly the least harmful of all the newer preservatives. While it would 

 be very convenient to preserve foods by their use, it is important that 

 nothing be added to foods which is toxic in itself, or which interferes even 

 to the slightest extent with the process of digestion. This last point is 

 especially important in dealing with the food of children and invalids. 



The preservatives now in use may be divided into two classes : those 

 which are undoubtedly injurious, such as formalin, the fluorides, salicylic 

 and sulphurous acids, and those whose toxic action is disputed. The 

 boron compounds belong to this latter class, and because of their exten- 

 sive use in preserving dairy products, are of especial importance to dairy- 

 men. 



Numerous methods have been made to ascertain whether the use of 



boric acid or borax in small quantities was or was not injurious, but no 



definite conclusions have been reached. Many distinguished English, 



German and French scientists have performed elaborate experiments with 



2 Bnl. 14.5 



