5S8 ANNUAL REPORTS OF THE DEPARTMENT OP AGRICULTURE. 



season work is being conducted at a ])lanL in Wicliita, Kans., to secure 

 data on desiccated eggs. Work of the same nature was done on 

 samples of reprocessed or ''do over" salmon and inferior grades of 

 sardines. 



Progress has been made in the study of the manufacture and the 

 chemical composition of gelatin in collaboration with the Washington 

 P'ood Inspection Laboratory. In collaboration with the Laboratory 

 of Plant Physiological ('homistry a series of feeding experiments with 

 bread on white rats and mice was started. Bread baked from ordi- 

 nary white flour, graham flour, and bread containing dift'erent per- 

 centages of cottonseed meal were employed in the experiments, Avhich 

 were controlled by the analysis of the broads, weights of the animals, 

 and the analysis and histological examination of the animals that died 

 during the tests and of those killed at the conclusion. 



MICKOCHEMICAL EXAMINATIONS. 



The microchemical investigations during the past fiscal year have 

 been similar in character to those carried on in previous years, con- 

 sisting largely of microscopical examination of samples. The volume 

 of work performed, however, has been very much lessened through the 

 resignation of two analysts and because of the time consumed in the 

 preparation and presentation of evidence in connection with cases 

 tried under the food and drugs act. 



Certain investigations, however, have been conducted in the nature 

 of sj)oilage of fruits and fruit products, nuts, and similar substances, 

 which, through careless handling, may have been seriously affected. 

 In the line of investigation of fruits visits were made to a few fac- 

 tories where such products were being packed, observations were 

 made as to the kinds of fruits used and the process of handling, and 

 samples of the finished product were examined microscopically. From 

 this work as a basis, standards for judging such products were ob- 

 tained. 



The work begun last year upon the subject of insect powder for the 

 determination of the amount of stem present in normal pyrethrum has 

 been continued as far as time available for such w^ork would allow. 

 A trip was made to an establishment where the flowers were being 

 ground, and samples were taken of the product before and after 

 milling for the purpose of obtaining standards from which to judge 

 of the amount of stem present in unknown samples. 



During the fall of 1911, at the request of the Treasury Department, 

 an investigation was begun on the question of detection of coloring 

 matter and facing on teas. This investigation showed that a great 

 proportion of tea was artificially colored or faced and resulted in the 

 devising of a new method, which has, with certain slight modifica- 

 tions, been adopted as the official method of the tea testers of the 

 Treasury Department. 



The microscopical examination of proprietary, infant, and invalid 

 foods in collaboration with the section of animal physiological chem- 

 istry has been in progress and many samples have been examined. 

 It has been shown that the microscopical examination of these prod- 

 ucts gives information, not only as to the ingredients used, but also 

 as to the method of manufacture and incorporation of the ingredi- 

 ents. 



