The most common substance added to butter as a preservative is 

 salt. The use of salt, together with the practice of storing butter in 

 such a manner as to exclude air and light to prevent oxidation of the un- 

 saturated fats, and at a low temperature to retard the action of ferments, 

 has been, on the whole, fairly successful in retaining the good qualities 

 of butter. In our export trade, however, new conditions are arising, and 

 the dairyman has now to cater to a market which demands practically a 

 saltless butter. • To meet these new conditions he is compelled to cease 

 using the only preservative with which he is familiar. Further, many 

 creameries are not provided with cold storage plants, and are thus not 

 able to use even this method of lengthening the commercial life of butter. 

 Under these conditions it is not strange that butter-makers have com- 

 menced to use some of the brands of preservatives which are now so ex- 

 tensively advertised, especially when their use is advised by the whole- 

 sale dealers to whom they sell. 



Chemical Preservatives. 



It is only in comparatively recent times that the real nature of fer- 

 mentation, decay, and all such cases has been clearly understood. From 

 time immemorial foods have been preserved by drying, smoking, placing 

 in strong brine, in alcohol, or in vinegar, but it was not until after the 

 work of Pasteur and others had shown that fermentation and decay are 

 primarily caused by minute organisms, and that these organisms could 

 not grow without m.oisture, in salt solutions, alcohol, or vinegar, that .the 

 true nature of these methods of preserving foods was understood. " 



Concurrently with the development of the science of bacteriology 

 the study of chemistry has made known many chemical compounds which 

 will destroy or retard the growth of these organisms. Many of these, 

 such as bichloride of mercury, sugar of lead, etc., while powerful preser- 

 vatives, are very poisonous, and for obvious reasons could not be utilized 

 as food preservatives. In order to be used for this purpose, a substance 

 must be almost without taste or smell, it must not be so noxious as to 

 cause any immediate or serious results to the health of the consumer, it 

 must be comparatively cheap, and yet so strong in its action on the lower 

 organisms that only a small amount need be added to the food which it is 

 desired to preserve. It is evident that the presence of small quantities of 

 such substances in food would not be noticed by the consumer. In this 

 they differ from the old preservative agents, such as sugar, salt, etc., 

 which are condimentary in character, and reveal themselves by taste to 

 the consumer. 



At the present time the chief chemical compounds, other than salt, 

 sugar, and alcohol, used in the preservation of foods are as follows : 



1. Boric or boracic acid and borates. 



2. Formalin or formaldehyde. 



3. Salicylic acid. 



