488 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



pleted, and the special investigation of the production of citrus 

 by-products in California, begun hist year, is being continued. The 

 nielhods for the manufacture of citric acid have been studied in the 

 laboratory and the investigation is now awaiting the completion of a 

 device for extracting oil. Whether or not such a device can be suc- 

 cessfull}^ operated will soon be ascertained. 



DisTTLLEo SPIRITS. — The investigation of the methods of handling 

 distilled spirits and the study of the changes taking place in storage 

 of same under varying conditions, which was commenced two years 

 ago, is still being carried on, samples being taken at regular intervals 

 and general conditions noted. The data so obtained are of value in 

 judging of the authenticity of samples in the enforcement of the 

 food law. 



Cider vinegar. — A special study has been made of the changes 

 taking place in the composition of apple cider when converted into 

 vinegar in the commercial types of generators. In order to deter- 

 mine what changes take place when manufacturing on a commercial 

 scale, the cooperation of a large vinegar factory in Michigan was 

 obtained, thus making it possible to exercise chemical control of all of 

 the operations under commercial conditions. Twice during the year, 

 once 111 the winter and once in the summer, a 20,000-gallon tank of 

 cider was run through a series of generators, and a careful note made 

 of the changes of composition which occurred, thus covering also the 

 effect of the seasonal changes in temperature on the action of the gen- 

 erators. This work is still in progress, and already important in- 

 formation has been obtained as to the composition of pure cider 

 vinegars made on a commercial scale. In addition to the study of 

 changes taking place in the manufacture of cider into vinegar, an 

 elaborate chemical study of the composition of cider to be used in 

 the manufacture of cider vinegar has been made in cooperation with 

 the New York laboratory. 



Occurrence of arsenic in food products. — The investigations of 

 the Bureau have shown that certain materials, used both as drugs 

 and in the manufacture of foods, sometimes contain a considerable 

 amount of arsenic. For example, a number of samples of various 

 types of foods, in the manufacture of which commercial preparations 

 of phosphates and phosphoric acid were used, were found to contain 

 an excessive amount of arsenic. A study has been begun to determine 

 the prevalence of the use in the manufacture of foods of arsenic- 

 bearing raw materials. 



Oysters. — A number of cove-oyster canneries have been visited 



and samples prepared in the presence of the inspector have been 

 examined in the laboratory. The data secured are of value in judging 

 of the legality of shipments of cove oysters in interstate commerce. 



Influence of tin receptacles on the character and composition 

 of foods. — A careful study has been made of a large variety of foods 

 canned in different grades of tin and prepared in the presence of 

 representatives of the Department. This food will be examined 

 periodically to determine the amount of tin dissolved therein and the 

 extent to which the coating of the receptacle has been corroded. 

 During the past year the first examination of all of the samples was 

 made. For the same purpose there were examined some old samples 



