The extent to which tannin extract production is itself an agricultural operation is indicated and the distribution of tannins in the plant kingdom discussed. Present knowledge of the nature of the tannins is summarized and illustrated, by reference t o specific extracts. The problem of the biological origin and function of tannins is discussed, particular reference being made to the effect of these substances on viruses. Brief mention is made of the effect of tannins on soils which they may disperse or aggregate to a marked extent.U N D E R present-day conditions, not only are tannins becoming of increasing importance as raw materials for industrial chemical processing in their own right, but their production also represents an agricultural operation of appreciable magnitude. The present world annual production of tannin extracts is of the order of 500,000 tons. Four extracts represent the bulk of this and are available in reasonably standardized form :(4 (ii) Quebracho extract, from the heartwood of Schinopsis Zorentzii or the related balansaeWattle (mimosa) extract, from the bark of Acacia moZlissima-annual production (iii) Chestnut extract, from heartwood and sapwood of Castanea sativa and dentata-annual (iv) Myrabolam extract-from the dried fruits of Terminalia chebula and related speciesthe annual production ranging from 200,000 to 2 j0,ooo tons. approximately 120,000 tons.production something under IOO,OOO tons. annual production probably above 20,000 tons.A variety of other extracts are also commercially available in smaller quantities.Of the four mentioned, only wattle extract is produced by an organized agricultural operation in that the source tree is grown to a standard cycle in plantations planned and planted as such. Some 8jo,ooo acres of African soil are under wattle cultivation, mainly in the Union of S. Africa, and the industry has its own Growers Research Association co-operating closely with the research staffs of the major extract-producing firms. All aspects of growth, cultivation, genetics etc. are receiving the same intensive scientific attention as is customary with the world's major food crops.Quebracho extract is produced from natural stands of timber in the Argentine and Brazil, and although collection of the trees is organized, cultivation is not. The Forestal operations represent some 50% of the total and involve the ownership of about 2,500,000 acres of land.Corresponding figures for the acreage of European chestnut forests and of the Indian forests in which Terminalia spp. occur as a component are not available, but would certainly be quite large. Definition of ' tannins 'The term was first used by Seguinl in 1796 to indicate the material present in oak gall nuts, responsible for the formation of leather when hide was treated with aqueous infusions of the galls. Before this time tannage had been regarded as a physical process which caused shrinkage of raw hide and depended on an ill-defined astringent property of certain plant infusions-the fact that chemical substances were involve...

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King et al.: Occurrence of 2-Benzyl-2-hyd~oxycou~a~an-3-ones 635. The Occurrence of 2-Benzyl-2-hydroxycournaran-3-ones in Quebracho Tannin Extract.

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In order to achieve the advantages of automatic operation, an automatic quartz tube oomhustion apparatus has been developed for the determination of sulfur and halogens in organic materials. The sample is vaporized in a stream of nitrogen and combustion occurs in the high temperature zone of the combustion tube, where a stream of oxygen is injected. A thermooouple, located just beyond the point at which oxygen is introduced, senses the heat generated by the combustion of the sample vapors and controls the amount of heat that is applied to cause vaporization of the sample. The apparatus reduces the training which must be given the operator, eliminates improper combustions resulting from errors in judging the volatility of samples, and automatically burns each sample at the maximum safe rate. An operator oan complete 15 to 25 analyses per 8-hour day with virtually no possibility of losing an analysis heoause of improper combustion.HE quark tube combustion method ( 1 ) is widely used in the T petroleum industry for determining sulfur and halogens in organic materials. I n this method the sample, contained in a combustion boat, is vaporieed in a stream of air by gradually applying heat to the sample boat. This technique requires the constant attention of the operator, and his experience and training are important factors in achieving properly controlled vaporization of the sample.In attempts to design an apparatus which would allow more rapid combustion and would facilitate the combustion of volatile materials, a unit was constructed in which the sample was vaporized in a stream of nitrogen and the vapors were mixed with oxygen within the heated zone of the combustion tube. The observation that an intense flame resulted in the zone of admixture of oxygen and sample vapors suggested the possibility of Using the flame temperature as a measure of the rate of sample vaporization. In preliminary tests a thermocouple was located in the flame and the temperature indicated by a pyrometer was used to guide the rat0 at which heat was manually applied to vaporize the sample. The direct relationship found between the flame temperature and sample vaporization rate suggested that the former could be used as the basis for automatic control of the latter. As a result of further investigation along these lines, an apparatus was developed which provides completely automatic sample combustion.Combustion is carried out in a horizontally mounted quartz tube, a portion of which is maintained at 1000' C. The sample is placed in the cool zone of the tube and rapidly heated by applic* tion of full line voltage to a bare wire coil on the outside of the tube. Sample vapors are swept into the heated zone by a stream of nitrogen and mixed with a large excess of oxygen, at which point they burn with an intense flame. The rate of sample vaporization is controlled by a thermocouple located in this flame. The thermocouple, by means of an amplifier and relay circuit, switches the heater off and turn8 on a cooling air blast, or switches the heater on ...