April, 1918 C. U. C. P. ALUMNI JOURNAL 53 



Potted Meats, Fish and Fatty Substances. — The material should be sep- 

 arated into small particles or the fibers teased apart. Of the sample so prepared, 

 not less than lOO grams should be extracted with ether or other solvent to remove 

 most of the fat. After extraction, the organic materials in the residue art- 

 removed by treatment with concentrated hydrochloric acid with potassium chlorate 

 added in small quantities. When destruction of the tissues is complete the liquid 

 is diluted with water and the sand, glass or other insoluble matter collected by 

 filtration. This adaptation of toxicological technic proves very .satisfactory for 

 most foods of animal origin, with the possible exception of cheese. In the 

 case of the latter foodstuff destruction of the organic matter by the above method 

 is very slow. For rapid disintegration of cheese, heating with a mixture of con- 

 centrated sulphuric and nitric acids in a Kjeldahl flask gives good results. The 

 insoluble residues in each case are reserved for microscopical examination. 



Breads and Baked Flour Products. — If quantitative results are de- 

 sired, the material should be disintegrated, well dried and the loss of moisture 

 determined. After this preliminary, the breadstuff should be reduced to coarse 

 powder (20 mesh). Large quantities (200-400 gms.) of the sample should be 

 used. The organic matter may be removed by the chlorine treatment described 

 in the preceding paragraph and the residue collected for further examination. 

 A more rapid method but one in which results are not as accurate, consists in 

 boiling the sample with sodium hydroxide solution (10%) for at least two 

 hours. This treatment results in the disintegration of most of the starch and 

 protein. Bran tissues may resist solution but can be separated from the other 

 insoluble materials by either of the methods following. The liquid after treat- 

 ment with the alkali is reduced to small bulk by careful decantation, the insoluble 

 material washed nearly free of alkali, neutralized by dilute hydrochloric acid and 

 the whole transferred to a large separatory funnel containing chloroform. When 

 the mixture is gently agitated the bran tissues will separate at the junction of the 

 water and chloroform layers while the heavier materials will sink to the bottom 

 of the funnel and may be withdrawn. After evaporation of the chloroform, 

 the sand or glass will be in shape for weighing and microscopical examination. 



Flours, Meals and Uncooked Flour Products. — Weighed quantities of 

 the suspected product are placed in a large separatory funnel having a short 

 but wide outlet tube and stopcock drilled with a large opening. About 100 mils 

 of chloroform should be added to the sample in the funnel and the mixture well 

 shaken, after which the funnel should stand in a vertical position for at least 

 three hours. Foreign materials, aleurone and some starch will deposit and 

 should be drawn off into a shallow crystallizing dish. After evaporation of the 

 chloroform, this residue is in shape for microscopical examination. If quantita- 

 tive data is required, the insoluble and heavier materials should be drawn off into 

 a beaker and the residue evaporated to dryness. Sodium hydroxide solution 

 (10%) is added to this dry residue and the mixture thoroughly boiled to remove 

 the small amounts of aleurone and starch contained. After this treatment the 



