CHAPTER XVIII 

 DETECTION OF ADULTERATIONS IN FOODS AND DRUGS 



How to Begin. — The microscope is indispensable to the 

 detection of adulterations in powdered foods and drugs, and the 

 enforcement of our pure food laws will require men skilled in 

 the application of the microscope to this kind of research. 



Before proceeding with the microscopic examination of a 

 powder a knowledge is necessary of the histology of the plant 

 part which is supposed to constitute the powder. If, for example, 

 powdered cinnamon is to be investigated, the different kinds of 

 cinnamon barks on the market must be obtained for study, 

 from a reliable source, and these must be examined in cross and 

 longitudinal sections and in powdered form. The directions 

 that will now be given for the study of cinnamon bark will serve 

 for dried barks and woods in general. The bark is hard and 

 brittle and will need to be put in better condition for sectioning. 

 Place in warm water and let it soak over night, and then trans- 

 fer it to equal parts of alcohol, glycerine, and water and let it 

 remain there for two weeks — the longer the better. It can then 

 be sectioned free-hand (see page 251), while held between two 

 pieces of cork free from grit; or it can be sectioned in a sliding 

 microtome (Fig. 143). Keep the knife wet with 70 per cent, 

 alcohol and transfer the sections to a watch-glass of water. 

 Mount the sections for the first study in a drop of dilute glycer- 

 ine. Water would do but it may evaporate before the examina- 

 tion is completed. If it is found that the thinnest sections are 

 too opaque to make the cells out clearly they may be remounted 

 in a drop of saturated chloral hydrate solution. In this case or 

 in any other where the material has become dry and brown if 

 the chloral hydrate does not clear the sections well enough they 



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