th 

 su 



NATURE OF ADULTERATION. 7 



are allowed to lie in the field in order that they may become partially 

 cured, or they are immediately taken to the barn for curing. It is 

 important that the material be not exposed to rains or to intense sun- 

 shine during curing, as the quality of the product is greatly injured 

 thereby. As a rule, therefore, the best product may be obtained by 

 drying under cover, being careful to turn the leaves frequently to 

 prevent molding. After drying, the leaves and stems are roughly 

 ground, baled, and sold as "leaf sumac," or they are reground in 

 edge runner mills, sifted to remove the stems, ventilated, bagged, and 

 sold as "ground sumac." 



It can readily be seen that the dryness of the product and the 

 proportion of stems that remains with the leaf of the baled and 

 ground sumac will vary considerably according to the care with 

 which it is handled. As these stems not only contain less tannin, 

 but also have a deeper color than the leaf, the value of the product 

 may be materially influenced simply by the method of preparation 

 for market. 



NATURE OF ADULTERATION. 



In addition to the incorporation of large quantities of the stem 

 with the leaf, a practice which must be regarded as an adulteration, 

 a number of other materials less valuable for tanning than sumac are 

 mixed with the leaf. By far the most common adulterant, indeed 

 the one almost exclusively used in the sumacs imported into this 

 country, is the leaf of Pistacia lentiscus commonly called lentiscus 

 or lentisco. This leaf contains from 12 to 20 per cent of a catechol 

 tannin, and leather tanned with sumac adulterated with this leaf 

 darkens and reddens on exposure to air, for which reason its use 

 is decidedly objectionable in the manufacture of certain grades 

 of leather. The lentiscus is mixed with ground sumac at the rate 

 of from 20 to 50 per cent, and with the sumac leaves at the rate 

 of 20 to 30 per cent. Other leaves much less generally used in adul- 

 terating sumac are those of Coriaria myrtifolia ("stinco"), Tamarix 

 afmcana ("brusca"), Ailanthus gladulosa, Vitis vinifera (grape 

 vine), and some species of the Rhus family other than coriaria, as 

 well as foreign material. Sumac from which tannin has been 

 extracted or which has been injured by exposure is also mixed with 

 the normal product. None of these adulterants can be detected 

 by a casual examination of the sumac, but special methods, which 

 will be described later, have been devised for this purpose. 



The Italian laws require that all adulterated sumac offered for 

 export shall be distinctly labeled with the kind and quantity of the 

 adulterant, but it is claimed that this law is frequently evaded, and 

 the trade journals state that a very large percentage of adulterated 

 sumac has been shipped to this country. Some have tried to justify 



117 



