U. S. DEPARTMENT OF AGRICULTURE, BUREAU OF CHEMISTRY-BULLETIN No. 117. H. W. WILEY, Chief of Bureau. COMMERCIAL SICILIAN SUMAC. By F. P. VEITCH, CHIEF OF THE LEATHER AND PAPER LABORATORY. INCLUDING NOTES ON THE MICROSCOPICAL EXAMINATION OF SICILIAN SUMAC AND ITS ADULTERANTS, LETTER OF TRANSMITTAL. UNITED STATES DEPARTMENT OF AGRICULTURE, BUREAU OF CHEMISTRY, Washington, D. C., June 3, 1908. SIR: I have the honor to submit for your approval a report of two investigations, conducted in 1905 and 1907, concerning the quality of Sicilian sumac imported into this country, chemical and microscopical examination of a large number of samples having been made. This study was made in the Leather and Paper Laboratory of the Bureau of Chemistry because of its direct bearing on the leather trade interests of the country, as well as because of its relation to the increased production of sumac in the United States. Material assistance in the performance of the laboratory work involved in this investigation was rendered by H. H. Hurt and C. C. Smoot, of the Leather and Paper Laboratory. I recommend the publication of this report as Bulletin 117 of the Bureau of Chemistry Respectfully, Hon. JAMES WILSON, Secretary of Agriculture. H. W. WILEY, Chief of Bureau. 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. |