INTRODUCTION. 



The amount of work which was necessary for the preparation of this 

 important part of Bulletin 13 has postponed its publication far beyond 

 the time originally intended. It was thought better, however, to 

 withhold the manuscript from publication until the analytical work 

 had not only been accomplished, but further until any doubtful points 

 could be reviewed and any uncertain matter eliminated. To this end, 

 all of the analyses of a doubtful nature were repeated, if necessary, 

 with fresh samples purchased in the open market. In addition to this, 

 in all important cases the results of the analyses were submitted to the 

 manufacturers for the purpose of permitting them to make any repre- 

 sentations in regard to the analytical data which might seem advisable 

 before their publication. It often happens that deleterious substances 

 or other adulterants are found in articles of manufactured foods with- 

 out knowledge of their presence on the part of the manufacturers. 

 This is due chiefly to the purchase by the manufacturer of certain of 

 the materials in a manufactured or partly prepared state. In many 

 cases these materials contain preservatives or other adulterants, and 

 thus these matters find their way into the finished product. 



In work of this kind we desire to safeguard in every possible way 

 the interests of the consumer and the trade, which are also the inter- 

 ests of agriculture, since the object of our work is not solely to study 

 foods in regard to their composition and the adulterants which they 

 may contain, but further to establish the purity and wholesomeness of 

 staple articles of food so that the -consumer may have a reasonable 

 assurance in their purchase that he is securing that which he desires. 



For the purpose of carefully studying the finished manufactured 

 foods, it is highly desirable that a knowledge of the technical processes 

 employed be secured. To this end, a member of the Bureau has vis- 

 ited many of the establishments where preserved meats are prepared, 

 for the purpose of studying the technical processes and of personally 

 informing himself on the precautions employed to secure freedom 

 from contamination, adulteration, and other impurities. 



Further than this, in order to gain a more perfect knowledge of 

 the changes which were produced in the processes of preservation, 

 the foods have been prepared in many cases in the laboratory. By 

 this means the composition and character of the original product can 



