Theine is soluble in about 100 parts of hat water. It vaporizes at 185 degrees C. or 365 degrees Fahr., hence it is not driven off by continued boiling of tea infusion. W. Dittmar found by experiment that prolonged steeping of tea leaves up to ten minutes increased the proportion of theine in the infusion. His results are as follows: STEEPED 5 MINUTES. Average of 8 samples Chinese tea: Theine, per cent infusion--2.58 Tannin--3.06 Average of 6 samples Ceylon tea: Theine--3.15 Tannin--5.87 Average 12 samples of Indian tea: Theine--3.63 Tannin--6.77 STEEPED 10 MINUTES. Theine, per cent infusion--2.79--Increase about 10 per cent Tannin--3.78--Increase about 25 per cent Average of 6 samples Ceylon tea: Theine--3.29--Increase about 5 per cent Tannin--7.30-- Increase about 25 per cent Average 12 samples of Indian tea: Theine--3.73--Increase about 3 per cent Tannin--8.09-- Increase about 20 per cent W. M. Green reported that in prolonging the steeping of tea from 10 to 20 minutes, he observed the formation of a tannate of theine, which diminished the proportion of 1.30 per cent. of theine at 10 minutes to 1.16 per cent. after 20 minutes steeping, a loss of about 10 percent., unless the latter salt so formed is proved to yield up its theine constituent in the human stomach. While theine is credited as the source of the most powerful and useful properties of tea, and without which no plant would be recognized as tea, yet some of the stimulating or exhilarating influences of this plant are attributed to the volatile oils which contribute so largely to the flavors and odors which characterize tea. These Essential or Volatile Oils of manufactured tea are said to reside in the minute cells of the green leaf, but they are greatly changed by manipulation, for they are not manifest to the sense of taste or smell when expressed from the green leaf by bruising, nor does the green leaf yield their aromatic flavors to an infusion. Professor Johnston says that these precious oils are artificially developed by manufacture. David Crole declares that they are developed "to a certain extent during withering, and also during the first stage of firing," which last process, if carelessly conducted, "oxidises it (the oil) into resin." Green tea, they first remove from the green leaf, imparts very little flavor or scent to its infusion. In some Oolong Black teas, and in some Ceylon Black teas, these oils are highly developed and are very fragrant. In the black Souchongs and Congous they have again been altered by treatment, but are no less perceptible, and to many, are quite as agreeable. Although constituting only one-half to one per cent. by weight of the dried leaf, these oils are all-important to the trademan and to the consumer.