and its adulterants give a precipitate on treating with a quantity of saturated bromin water, and, as a consequence, but little reliance can be placed on this test. One of the most reliable indications of adulteration is the color of the dried sample. If lentiscus is present it will darken greatly on heating, becoming a dirty light brown with a tinge of red, while pure sumac only turns a slightly darker yellow. The experienced analyst, having a pure sumac for comparison, can pick out in nearly all cases samples adulterated with lentiscus. That this test agrees well with the microscopical examination is shown by the last column of Table II, where the purity of the samples as indicated by the color after drying is given. Of a total of 91 samples examined, 82 agreed with the microscopical test, 3 were doubtful, and 5 were erroneous. Moreover the color of the extract has been found a valuable indication, samples adulterated with lentiscus giving a dark reddish extract, easily distinguished from pure sumac. As a rule, therefore, the experienced analyst can distinguish by means of the color of the extract and the dried material those samples which are adulterated with lentiscus, but if there is any uncertainty a microscopical examination must be made.

Neither the percentage of ash nor of sand is an indication of adulteration with lentiscus, as this leaf does not differ materially from sumac in these particulars. The samples of leaf and ground sumac contained on an average 1.41 per cent of sand, the highest amount found being 3.05 per cent. Assuming that there was no sifting out of sand in transit, there was no evidence of willful addition of sand to these samples, although several indicated that they were but imperfectly winnowed or ventilated. There was less than 1 per cent of sand in the unground leaf, while 106 samples of ground leaf averaged 1.62 per cent and 15 contained more than 2 per cent. Therefore 2 per cent of sand may very properly be considered the maximum sand content of a well-ventilated ground sumac. A larger content of sand indicates that the samples have been carelessly prepared.

117

EXTENT OF ADULTERATION.

From 25 to 41 per cent of the invoices of Sicilian sumac imported into the country are adulterated, and this adulteration is effected almost exclusively with lentiscus. These adulterated shipments are, as a rule, so labeled as to convey the impression that they are pure Sicilian sumac. It is sometimes claimed that shipments of sumac are mixed with lentiscus in accordance with the order of the importer. In such cases the consignment should be properly labeled indicating the amount of lentiscus used. The tannin content is from 2 to 7 per cent lower in the adulterated samples than in the pure sumacs, averaging about 4.5 per cent lower, and the color of the extract prepared from them is much darker than that of pure sumac extracts. While to the experienced analyst the color of the extract or of the dried material is generally indicative of the purity of the sample, only microscopical examination can definitely determine this question.

The adulteration of Sicilian sumac is of more importance than is indicated merely by a lower tannin content, otherwise American sumac could be used at a much smaller cost. When high-grade, light-colored leathers or durable sumac-tanned leathers are required, as for instance in bookbinding, adulteration results in discoloration and destruction of the leather in a much shorter time than when pure sumac is employed in tanning, and the money loss thus occasioned is many times the difference in cost between a pure and an adulterated

sumac.

Aside from any ethical consideration, there is absolutely no advantage to the tanner in the purchase of adulterated sumac because, as a matter of fact, the tannin in such sumac costs more for a given amount than when bought in pure sumac. Thus taking the current quotations of from $71 to $72 per ton for sumac containing 29 per cent of tannin, $70 to $71 for 28 per cent, and $69 to $70 for 27 per cent, the tannin costs from 12.2 to 12.4 cents, from 12.5 to 12.7 cents, and from 12.7 to 13 cents per pound, respectively. That is, the tanner is making a lower grade leather at a greater cost when using adulterated sumac. Finally, as there may be a variation of as much as 10 per cent in the tannin content of pure sumac, it should always be bought on the basis of its tannin content, and if adulterated should be so labeled.