Foods: their composition and analysis : A manual for the use of analytical chemists and others. With an introductory essay on the history of adulteration / By Alexander Wynter Blyth. With numerous tables and illustrations.

  • Alexander Wynter Blyth
Date:
1882
Catalogue details

Licence: Public Domain Mark

Credit: Foods: their composition and analysis : A manual for the use of analytical chemists and others. With an introductory essay on the history of adulteration / By Alexander Wynter Blyth. With numerous tables and illustrations. Source: Wellcome Collection.

Provider: This material has been provided by The University of Leeds Library. The original may be consulted at The University of Leeds Library.

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    roasted bean I broke into small pieces, and after infusing these in clear rain water, I suffered the water to evaporate after pouring it from the grosser parts of the coffee, and then I discovered a great mimber of oblong saline particles of different sizes, but most of them exceedingly minute ; all of them with sharp points at the ends and dark in the middle.* He figures these '• saline particles, and from the description and the figure they can be scarcely other than crystals of caffeine or theine. He also cut thin slices of the berry, and one of his plates is a very good illustration of the cellular structure of coflfee. He noted that it was of an open and spongy texture . . . and some of the parts which in the figure appear closed up, consisted of globules, and were filled with oil. Still more decisive are his observa- tions on tea, in which it is absolutely certain that he obtained caffeine or theine by sublimation, for he distilled it and collected the volatile salt. All these saline particles were of the same shape, that is, very long and pointed at both ends. . • . I afterwards endeavoured, for my further satisfaction, to discover, if possible, how many saline particles could be produced from a single leaf of tea ; but having reckoned up only a part of the volatile salts contained in one leaf, I forbore any furtlier observations, because the number I had already reckoned up was so gi'eat that I dared not publish it, as I had proposed to do, and indeed many persons could not believe that the leaf itself could be divided into so many parts visible by the microscope, as I saw volatile saline particles produced from one single leaf He also examined the ash of tea, and noticed its deliquescent character. He separated several distinct salts, of which one kind had small cubical crystals, and was probably common salt. He also turned his attention to pepper, and extracted from it a crystal- line principle, probably piperine. He powdered long pepper, and placed it in a glass vessel, covei'ing it with rain water to about one-third of an inch. After the water had stood about two hours, I poured it off, but it being evening I let the water stand all night. The next morning I saw in the place where it was most evaporated an incredible number of saline particles, many of which were almost twice as long as broad, but one side always longer than the other. Ho ahso distilled pepper, and extracted from it an oil. He considered the difference between white and black pepper to be that one was decorticated, the other not, and ])voved that he was i-iglit by direct experiment. In speaking of vineg.ir, he noticed that it was neutralised by chalk, and that it often contains ramute eels—these eels he figures and describes. The Select Works of Antony Van Lecuwenboek, 4to. Lond., 1798.
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