10 BULLETIIs^ 106^ U. S. DEPARTMENT OF ACtRICULTUEe. 



Examination of a number of unextracted sumac samples gave : Ash, 

 4 to 7.5 per cent; potassium oxid, 1.18 to 2.15 per cent. The ash of 

 these samples contained from 25 to 30 per cent of potassium oxid. 



Comparison of the percentage of potassium oxid (ICO) in the origi- 

 nal material and in the water extract, as obtained for the tannin 

 analysis, shows that although the unextracted sumac contains rather 

 high percentages of potassium oxid, as is to be expected, this is almost 

 enth'ely removed on extraction. These experiments were made on 

 finely ground sumac leaves and leaf stems, whereas in commercial 

 practice the extraction generally is made on the unground leaves 

 and stalks, and consequently is not so thorough, especially in the 

 case of the large stalks. This practice of making extraction on 

 the ungTound leaves and stalks midoubtedly accounts for the com- 

 paratively high percentages of potassium oxid in the samples of 

 commercially extracted stalks, analyses of which are given in Table 5. 



Except for the organic matter which it contains, extracted sumac 

 has comparatively little value for the. farmer. However, in sections 

 where sumac is gathered, where the land is usually deficient in organic 

 matter, the extracted material can be profitably hauled a mile or two, 

 especially if before scattering on the land it can be mixed and rotted 

 with barnyard manure. 



CAUSES OF POOR QUALITY IN SUMAC. 



Lack of care and attention to details in gathering and curing 

 results in sumac of inferior quality. Undue exposure to the sun 

 or any exposure to dew or rain while green, and heating and molding 

 resulting from too deep layers and insufficient turning during curing, 

 cause a decided darkening of the leaves and materially reduce the 

 percentage of tannin. The presence of stalks and red leaves in cured 

 sumac is objectionable, because they produce an undesirable color 

 on leather. Furthermore, since the stalks contain only about one- 

 fourth as much tannin as the leaves, their presence gives the mixture 

 a lower tannin content. The jDresence of dirt or sand in cured sumac 

 also is objectionable, for it increases the weight without increasing 

 the tannin content, and leathers tanned mth such sumac will darken 

 because of the iron present. 



COOPERATION FOR BETTER SUMAC. 



One of the objects of this bulletin is to point out the necessit}^ for 

 helpful cooperation between gatherers, dealers, and extract makers, 

 with a view to the production of higher-grade sumac and sumac 

 extracts and the payment of higher prices to the gatherers for better 

 sumac. This cooperation can be successfully maintained only if it 

 is mutually beneficial. The initiative and success rest with the final 

 buyers, the extract makers, who, by offering a bonus for "extra" 

 quality sumac, can encourage the gatherers to make special efforts 



