100 DEPARTMENTAL REPORTS. 



subjected to chemical examination. By this method a direct compari- 

 son was secured between the great number of meat products exam- 

 ined and the original fresh products from which they were made. 

 The amount of chemical work involved in this examination was of 

 great magnitude, and the bulletin containing the data of this work 

 will consequently be of a bulky nature. It is now ready for submittal. 



An elaborate investigation was also made of tlie character of horse 

 meat, with the object of determining whether or not it is sold sur- 

 reptitiously in this country for beef and also to determine whether or 

 not when mixed with other meats, as in tlie instance of making sau- 

 sage, the parts derived from the horse could in any way be identified. 

 The two obvious methods of procedure which would be naturally sug- 

 gested in this case were followed, viz, (1) microscopic examination of 

 the meat fibers and (2) determination of the chemical comi^osition of 

 the mixtures. To this end mixtures of horse meat with other meats 

 in known proportions were made, converted into sausage, and after- 

 wards given to the analj^sts without their knowledge of its contents 

 for the purpose of determining whether or not horse meat was con- 

 tained therein. The microscopic efforts in this line were futile, since 

 it was not possible to discover with certainty the fibers due to horse 

 meat in a mixture of that meat with certain other forms previously 

 subjected to the vigorous action of the sausage grinder. 



In the study of the chemical composition as a means of discrimina- 

 ting between horse meat and other kinds of flesh, more favorable results 

 were obtained. The meat of the horse contains quite a large quantitj" 

 of a sugar-producing substance known as glycogen. Other common 

 edible meats, with the exception of the meat of the lobster, crab, and 

 crayfish, contain only small quantities of this substance. It is evi- 

 dent, therefore, that a determination of glycogen in a mixture would 

 be a valuable indication in regard to the origin of the meats therein 

 in so far as the liorse is concerned. When the elucidation of this 

 problem was begun, however, it was discovered that none of the 

 accepted standards of examination was satisfactory. It was, there- 

 fore, first of all necessary to develop, by modification and otherwise, 

 a method of determining glycogen in horse meat which was reasona- 

 bly accurate. This, happily, was accomplished, and we were then 

 able to detect the presence of horse meat in a mixture, provided the 

 amount thereof was not reduced to too Ioav a percentage. Working 

 with the greatest care, it is believed tliat as little as 10 per cent of 

 horseflesh with beef can be detected with certainty by the methods 

 used in this laboratory and described in full in the forthcoming bulle- 

 tin above i-ef erred to. 



Not only is it possible to use the glycogen content for the purpose 

 of detecting a mixture of horse meat in sausages, but the iodin num- 

 ber of the fat is also valuable. The iodin al)sorption of the fat of 

 horse meat is very distinctly liigher tlian that of bc(4", wlien botli are 

 determined in the fresh state, and this is an additional evidence on 

 which a disci'imination between the two can be based. 



In the case of smoked meats, however, this number is not so valu- 

 able, since it has been found that in the fat of beef after smoking, the 

 iodin number is markedly higher than it was before. 



INVESTIGATION OF IMPORTED FOODS. 



Under renewed authority from Congress, the work of the inves- 

 tigation of the character of imported foods was carried on during 



