ILLUSTRATIONS. Page. PLATE I. Fig. 1.-Sicilian sumac (Rhus coriaria), upper surface. Fig. 2.- 28 II. Fig. 1.-Lentiscus (Pistacia lentiscus), upper surface. Fig. 2.— 30 III. Fig. 1.-Tamarisk (Tamarix africana), showing papillæ of epider- 30 COMMERCIAL SICILIAN SUMAC. QUANTITY AND VALUE OF IMPORTED SUMAC. Sicilian sumac is the best vegetable tanning material known for pale colors and soft tannage, and is consequently extensively used for moroccos, roans, skivers, etc., and for brightening the color of leather tanned with dark materials. An extended investigation" by a committee of the Society of Arts has shown conclusively that sumac-tanned leathers are less likely to be attacked by light and gas fumes, and hence better suited for use in bookbinding than any other known vegetable tannage. As good "masculino," or Sicilian mountain sumac, contains from 25 to 35 per cent of tannin which is absorbed by hides, it is a very high grade and desirable tanning material, commanding a high price. Consequently it is adulterated to a considerable extent, and much complaint has arisen during the past three or four years both from importers and tanners about the mixing of sumac leaves with stems or other lower-grade and darker-colored substances, an adulteration which not only affects the material itself, but also darkens greatly the leather tanned. In view of these facts it has been deemed advisable to make a careful examination of imported Sicilian sumac. Although mineral tanning has largely replaced vegetable tanning in the production of morocco, the importations of foreign sumac have remained about the same for a number of years, as shown by Table I, prepared from statistics issued by the Department of Commerce and Labor. TABLE I. Quantity and value of sumac imported into the United States from 1870 to 1907. CULTURE AND PREPARATION FOR MARKET. Sicilian sumac (Rhus coriaria) is a shrubby bush which grows chiefly in Sicily and Tuscany, and succeeds on any well-drained soil, though the best development is secured in calcareous soils. That grown in the mountainous districts around Palermo is known as 'masculino" and contains the highest percentage of tannin-from 25 to 35 per cent-while that grown on the plains is called "feminella" and usually contains less than 25 per cent. Andraesch" states that "feminella" is a variety distinct from "masculino," stronger, having larger leaves, and containing a darker tannin but less of it than the "masculino." Examinations of both kinds of leaf have failed to show any differences, and communication with importers brings out the fact that no distinction is made except on a basis of the tannin content. While in this country no attention is devoted to the cultivation of the native sumac, in Sicily it is commonly cultivated, as the yield and value of the leaf are both much greater than from the wild plant. Sumac may be grown on poor, stony, volcanic, or calcareous soils, not too far from the sea, and on mountain sides well exposed to the sun. Sudden changes of temperature or frequent rains, especially when the material is about ready to harvest, greatly injure its quality and strength. The plant may be propagated from the young shoots which form each year about the mature plant, from cuttings of the well-ripened stem, or from the seed. The first method is the one generally followed. The shoots should be at least a foot high, be well supplied with buds, come from young, healthy plants, and have short chain roots well supplied with rootlets. When cuttings from the wood are made, they must be first rooted in a propagation frame at a temperature of about 70° F. The young plants are set in well-cultivated land in rows 2 feet apart, and are given three or four cultivations during the growing season to keep the land free from weeds and grass. The first crop is harvested the year after planting, either by pruning or by picking the leaves. Harvesting begins about the middle of July, the time being governed by the development of the leaf, the object being to harvest when the leaf has acquired the deepest green color and reached its maximum weight. If the leaves are gathered by hand, harvesting begins when the first and lowest leaves have reached maturity, usually in May, and two subsequent gatherings are made as the younger leaves become fully developed, once late in July or early in August, and again in September, when the extremities of the branches are gathered. After being picked, the shoots and leaves a Abs., J. Soc. Chem. Ind., 1898, 17: 774. 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 sunshine 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 adulterating sumac are those of Coriaria myrtifolia ("stinco"), Tamarix africana ("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 |