172 



FOODS AND FOOD ADULTERANTS. 



whether the flour of mustard is a mixture of the two varieties or from 

 one alone. Mounts in chloral hydrate, to a certain degree, are use- 

 ful for adding to the transparency of the substance. The interior of 

 the seed is made up of small soft parenchyma cells containing the oil 

 and other constituents of the mustard, but without any trace of starch. 

 For this reason the presence of starch is a certain indication of the ad- 

 dition of some diluent of a farinaceous nature. Simple treatment with 

 iodine will therefore reveal the presence of wheat flour, which is a com- 

 mon adulterant of this condiment. The white color of the flour of 

 course reduces the yellow color of the mustard, and it is usual, there- 

 fore, to restore the tint by either turmeric or Martin's yellow. 



FIG. 10. Husk of white mustard, a, b, plasma layer ; c, sub-epidermal ; d, epidermis 



The former can be detected by a mechanical separation or a brown 

 coloration with ammonia or by the peculiar color cells which it contains 

 and the starch granules of the arrowroot class. The latter is not suffi- 

 cient in amount to be confused with potato starch or that of flour. It 

 has been already described. 



Martin's yellow can be identified by extraction with cold 95 per cent, 

 alcohol and examination, after evaporation of the solvent, as suggested 

 by Waller and Martin, and this coloring matter seems to be often used, 

 and cannot be pronounced as harmless as turmeric. 



The substances mentioned are the common adulterants of mustard, 

 in fact, so common that they have been accepted as necessary dilu- 



