2G8 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



A thorough chemical study of the fat of hogs fed upon cotton-seed 

 meal has bfon made, and a report is being prepared for publication. 

 The general results of the work showed tiiat tlie fat of hogs fed on 

 large quantities of cotton-seed meal is abnormally soft and abnor- 

 mally rich in the glycerids of the unsaturated fatty acids. In confir- 

 mation of work carried out l)v previous investigators the fat of these 

 hogs Avas found to give the Ilalphen and Becchi tests for cotton-seed 

 oil, but it does not contain ph^^'tosterol, thus permitting ready distinc- 

 tion between the fat of this character and fat to which cotton-seed oil 

 has been added. 



The investigations concerning meat extracts, referred to in my 

 report for the previous year, have been continued and have resulted 

 in the adoption of definite rules governing the preparation of meat 

 extracts at establishments at which federal inspection is maintained. 



An investigation of the action of fats and oils on metals was under- 

 taken primarily in order to determine the effect of fats and oils on 

 galvanized iron, which has been in the past used extensively for con- 

 structing containers for lards and lard substitutes and has also been 

 used for lining oleo seeding trucks and for making baker's drums and 

 similar metallic receptacles. As a result of this investigation it was 

 found that practically all metals, zinc in particular, are attacked by 

 fats and oils, and the use of zinc-coated vessels as permanent con- 

 tainers for meat or meat food products in establishments operating 

 under federal inspection has been prohibited. The results of this 

 study have been prepared for publication in the Twenty-sixth Annual 

 Eeport of the Bureau. This study is being extended to include the 

 effect of meat food products in general upon metallic containers. An 

 investigation of solders and fluxes now used in the manufacture and 

 sealing of metallic containers for meat food products, together with a 

 study of the paints used for coating cans, is now under way. 



In view of the large number of permitted coal-tar colors offered 

 for use in coloring the casings of sausages, it has been necessary to 

 secure a satisfactory method for estimating any poisonous ingredients 

 in these colors. It has been found that arsenic is practically the only 

 poisonous substance which may contaminate these colors, provided 

 the colors themselves are pure. An extensive examination of this 

 question has resulted in the adoption of a modified Gutzeit test which 

 has enabled the analyst to determine the arsenic with a satisfactory 

 degree of accuracy. 



In my last report it was mentioned that the cause of the souring of 

 meats during curing was being studied. This work has been completed 

 and a report of it prepared for publication. The investigations have 

 shown that the souring of meat is due to the action of a specific spore- 

 bearing organism which is properly classified among the so-called 

 anaerobic putrefactive bacteria. In the paper which is to be pub- 

 lished a descri])tion of this organism is given and suggestions are 

 made which it is hoped will lead to a diminution of the percentage of 

 sour meats heretofore occurring in inspected establishments. 



An investigation to determine the effect of prolonged storage on 

 canned meats was begun during the fiscal year. A large number of 

 cans of corned beef, roast beef, and lunch tongue were prepared at one 

 of the large packing establishments. A chemical, histological, and 

 bacteriological study of certain of these cans w^as made shortly after 



