There is, perhaps, no subject on which there has been more declamation, for and against its properties and effects, than those of teas imported into this country by the companies trading from the different maritime nations of Europe to China and India. Nor has there been a controversy in which the health of the community has been so materially concerned, that has afforded so little direction of moment to those who would wish to ascertain the truth of such teas being either beneficial, injurious, or innocent in their effects. Amidst a mass of declamatory assertion so little intelligence is to be gained, that those who have had the greatest interest in being informed of the real qualities of teas, have most abandoned the enquiry before they obtained the least knowledge of what they sought. Either perplexed with abstruse science, or dissatisfied with assertion equally unfounded and unsupported, thousands have discontinued the research, and committed themselves to fatal experience. Thus have too many acquired a knowledge of the detrimental qualities of teas, by the ruin of their constitution. To avoid therefore such an inconvenience, the greatest care will be taken to prevent an indiscriminate reference to authors, whose sentiments can neither sanction adduced arguments or illustrate technical allusions. The enquiry will be made with some reference to science, but more to convince by demonstration than to confound by abstruse perplexities. So that, while empty declamation is avoided, the principles of truth are meant to be investigated by reason and experience. With this view, the Nature of Green, Souchong, and Bohea teas is first considered. To judge of the nature of these herbs with equal candour and propriety, it may be necessary to consider their qualities in relation to what are ascribed them, and what have been discovered by their analysis, and what have resulted from experience. The virtues that have been ascribed to them are chiefly, being a greatful diluent in health, and salutary in sickness, by attenuating viscid juices, promoting natural excretions, exciting appetite, and proving particularly serviceable in fevers, immoderate sleepiness, and head-aches after a debauch. It is also added to the list of their ascribed virtues, that there is no plant yet known, the infusions of which pass more freely from the body, or more speedily excite the spirits. To a person of any physical knowledge, these qualities will either appear contradictory in themselves, or rather ultimately injurious, than absolutely beneficial. As the full examination of these assumed qualities, by the rules of science, would require a volume, instead of a few pages, which the limits of this Essay will afford, the enquiry must be made as perspicuous as the necessity of brevity will admit. Allowing they are diluting in health, their constant use may so attenuate the liquids as to destroy their natural force and tensity. But Boerhaave says, there is no proper diluent but water; it is therefore evident it is the water, and not the tea, which is the diluting medium. With respect to its being an attenuative of viscid humours, it can never possess this virtue from being a diluent, for an attenuant acts specially on the particles, by diminishing their bulk, while the diluent acts upon the whole mass of the fluid.

The general body of the liquid may be diluted while the viscid humours remain unresolved. Indeed, the operation of an attenuant is not easily known; for many are surprised that a slight inflammation should be so difficult to dissipate. But their surprise would cease, were they to consider, that medicines act more generally upon the whole body than abstractedly upon the part affected. Suppose to attenuate some coagulated blood, six grains of volatile salt were given, how small a proportion must come to the part diseased, when these grains, by the laws of circulation, will mix with the entire mass of blood, consisting at least of thirty pounds!

Teas being said to promote natural excretions, can be no recommendation of what is generally used; for this constant effect must render them too copious, and thus, according to all physical experience, the blood must be thickened in the greater vessels, which frequently terminates in an atrophy.

The appetite being excited by the drinking of tea, is more a proof of its attrition of the solids than any stimulus to a wholesome desire of food. This quality accounts for the acrimonious effects too many have experienced by its use. Many have not only had their blood impoverished, but corrupted by the constant drinking of these teas. Whether it arises from any positive acrimonious salt it naturally possesses, or from any acquired corrosiveness from its mode of drying, is not here necessary to enquire: it is only requisite to state that a pernicious effect is too fatally experienced by those who are unfortunately its slaves.

How India tea can be serviceable in fevers is not easy to be understood; for, if it has that effect upon the nerves to excite watchfulness, it must greatly tend to increase, instead of diminish feverish symptoms. Dr. Buchan attributes even one cause of the palsy to drinking much tea or coffee, &c. and, in a note, he subjoins: “Many people imagine that tea has no tendency to hurt the nerves, and that drinking the same quantity of warm water would be equally pernicious. This, however, seems to be a mistake, many persons drinking three or four cups of warm milk and water daily, without feeling any bad consequences; yet the same quantity of tea will make their hands shake for twenty-four hours. That tea affects the nerves is likewise evident from its preventing sleep, occasioning giddiness, dimness of the sight, sickness, &c.”

With regard to India teas possessing the quality of exciting the spirits, this, like every other stimulus, either by constant use loses its effect, or unnerves the system it is meant to strengthen. The nerves through which the animal spirits circulate being, like the strings of a violin or harpsichord, too frequently braced, lose, at last, their natural tensity, and thus render the human frame one system of debility.

Having thus, as briefly as possible, stated that even their ascribed virtues are either derogatory to all physical principle, or else destructive to the constitution, from their constant use, the nature of India teas is next considered, with respect to what appears to be their chief component parts, from analyzation.

Teas have been found to consist principally of narcotic salts, some astringent oil, and earth. These being found in greater quantities in bohea than in green teas, those who have very sensible and elastic nerves must be seized with a greater tremor after drinking the former than the latter. The continual and regular influx of the nervous juices is stopped by their component fibres being contracted from the roughness and restringency of such decoctions. The force of the heat, or the brain’s propulsion of its nervous juice, being inferior to the resistance of the whole ramified fibres thus encreased by the sudden contraction and unequal motion, the flow of the animal spirits must be greatly impeded and disordered. In fact, the influx suffers a suspension, until the fibres, by relaxing again, admit their empty tubes to receive their appropriated liquids. Thus even green tea must, especially if taken strong and often, stop the natural circulation of humours, and produce the attendant defects of depression of spirits, deficiency of secretion, loss of appetite, decrease of strength, waste of body, and, finally, a total want of effective vigour in all the animal functions. But, as above observed, bohea tea possessing in greater quantity the pernicious ingredients, the vessels are thrown into momentary spasms and convulsive vibrations, by the relaxing power of the narcotic salts, and the contracting force of the astringent oil and earth. And here it must be noticed, that oil mixed with salt is rendered astringent: thus all vegetables, where a mixture of both prevails, are reckoned stimulating. The narcotic power of the salt is derived from its hindering the flux of the animal spirits through the nerves.

The stomach and bowels being weakened by the above causes, windy complaints or flatulencies are consequently produced. This caused Dr. Whytt, in his advice to patients afflicted with such diseases, to desire they would abstain from India tea, as one of the flatulent aliments chiefly to be avoided.

If the slightest external motion alone produces the following changes in the body, what effects may not be ascribed to the constant use of teas, which we find, as before stated, operate internally? A person in perfect health, having his nostrils only touched with a feather, cannot avoid his body being so convulsed as to produce what is commonly called sneezing. But if the number of muscles agitated, the force and straining of the body by sneezing, are considered; the slightness of the cause must excite no little astonishment; for this action is occasioned by the muscles of the scapula, abdomen, diaphragm, thorax, lungs, &c. and if the sneezing continues, an universal explosion of the liquids ensues: tears, mucus, saliva, and urine, are excreted. Thus, without any moist, cold, hot, dry, sulphur, salt, or any other internal or external application, an involuntary motion of all the solids and fluids is produced by a feather touching, in the slightest manner, the inside of our nostrils. But Boerhaave relates further, “That if sneezing continues a long time, as it will by taking one hundredth part of a grain of euphorbium up the nose, grievous and continued convulsions will arise, head-aches, involuntary excretions of urine, &c., vomitings, febrile heats, and other dreadful symptoms; and, at last, death itself will ensue.” It is therefore evident that the slightest bodies produce the greatest changes in the human frame.

Such is the power of certain particles upon the nerves, that the stomach will be thrown into convulsions that almost threaten an inversion, by taking only four ounces of a wine in which so small a portion of glass of antimony as one scruple is infused in eight pounds of the former. And what is still more remarkable is, that the glass of antimony remains not only undissolved, but, comparatively speaking, undiminished in its weight.

These being a few of the fatal afflictions which experience shews to be frequently the consequence of drinking India teas, its injurious nature is too evident to require any further investigation of either their ascribed or positive qualities. The next subject to be considered, relative to India teas, is their Preparation.

Among the different authors of any consequence that have written on the culture, preparation, and virtues of foreign teas, may be ranked Kampfer, Postlethwaite, Dr. Cunningham, Priestley, Lemery, Franchus, Meister, and Sigesbeck; as the limits of this Treatise will not permit a detail of observations from the whole of these writers, remarks can only be selected from the most principal of them. Most of the above, and many other, authors agree that the leaves are spread upon iron plates, and thus dried with several little furnaces contained in one room. This mode of preparation must greatly tend to deprive the shrub of its native juices, and to contract a rust from the iron on which it is dried. This may probably be the cause of vitriol turning tea into an inky blackness. We therefore do not think with Boerhaave, that the preparers employ green vitriol for improving the colour of the finer green teas. It may however be concluded, from the colour of bohea, souchong, and such as are called black teas, that they may be thus tinctured, by the means of vitriol, after they have been dried upon the iron plates in the furnace room; and this may likewise particularly cause that astringent quality which is more experienced in all the black than any of the green teas. According to Sigesbeck, the colours of these teas are artificial; so that if these pernicious arts are used even to give the tea a particular colour, there is no difficulty in ascribing the cause of their injurious effects.

That the native virtues of these teas are liable to considerable perversion is evident from the manner in which Meister relates they are prepared. He says the leaves are put into a hot kettle just emptied of boiling water, and that they are kept in this closely covered until they are cold, when they are strewed upon the hot plates above mentioned for drying. It is easy to conceive how the virtues of a leaf, however salutary by nature, must be destroyed by such a process. Being thus put into a steaming kettle, and suffered to remain there until they are cold, must cause the greatest part of their Virtues to evaporate, and the leaves to imbibe an unwholesome taint from the effluvia of the steaming metal. It cannot, therefore, be ascertained whether teas that are imported in Europe, after such a mutating preparation, have the least remains of their original odour or flavour, no more than they have of their qualities; but, on the contrary, it seems impossible but that the original nature of this shrub is entirely destroyed by an artificial preparation. Some falsely suppose that this species of management is only to soften such of the leaves as are grown too dry, and are therefore liable to break in the curling; but this will evidently appear not the cause, when it is considered that the greater part of the teas must dry in such a hot climate while they are gathering: and as they are particularly anxious to send them in as curious a curled state as possible, such teas must be thus moistened again, in order to curl them afterwards in that perfect manner which is performed on the iron plates of the furnace.

The opinion, therefore, of teas deriving their green colour from being dried upon copper being founded on a misrepresentation of the manner in which they are really prepared, a few observations upon the subject are indispensibly necessary. For those who have always understood that the detrimental qualities of foreign teas were the consequence of their being dried upon copper, may perhaps imagine they cannot be so pernicious if they were dried upon iron; but this opinion cannot be entertained by any persons who have the least knowledge of the manner in which the vegetable acid will corrode iron. Those who are acquainted with culinary processes must know in what manner the acid of onions will operate upon any steel instrument; it corrodes a knife so as to turn the onions black with the particles eaten away from the edge and the face of the blade. To avoid this unwholsome and unseemly inconvenience, a wooden instrument is generally used in all instances where onions form a part of the cookery appendages. It is consequently evident, that although iron utensils are now greatly used instead of copper, yet many injurious effects may happen from their being liable to be corroded by the acid of several vegetables. And if the nitrous acid of the air will corrode iron so as to cause rust, when it will not produce the proportionate effect upon copper, it is a demonstration that iron is the most liable to such a corruption. The corrosions of copper are undoubtedly pernicious; but the damage that tea would derive from its being dried upon sheets of this metal would not operate so injuriously to those who drink it as it does now by lying dried upon iron. For the latter bring more liable to the power of the mineral, vegetable, or animal acid, must impart more particles of its reduced calax to the tea than copper would. And, in order to shew how susceptible of corrosion iron is, the following instance is farther adduced: in Ireland, where some persons practise the art of tanning leather with fern, which possesses a very strong acid, particular care is taken to avoid using any iron vessels in the tannage, lest the colour of the leather should be blackened by the corroding particle of the metal. As it is the peculiar property of iron or steely particles, even in their most perfect state, to operate as too great an astringent for an aliment that is taken twice a day constantly, tea, when dried upon it, must be rendered proportionably pernicious. But admitting that the popular opinion of their being dried upon copper was just, the teas must be rendered proportionably injurious to the quantity of copperas or crude vitriol they imbibe from their acidity corroding the metal. Preparations of steel, that are, in many instances, considered as most salutary, yet in all pulmonary disorders the most eminent physicians have deemed them exceedingly dangerous. And in a country, like Great Britain, Holland, and other places, where a cloudy atmosphere, caused from their marshy soil or watery situation, renders most of the inhabitants subject to complaints of the lungs, foreign teas, contaminated by these iron corrosions, must be particularly detrimental. It is therefore, from these considerations, evident, that foreign teas, by being dried upon iron, have their bad qualities so increased as to render them the most pernicious of any morning and evening liquid that has yet been taken. To return from whence we began this short digression.

It is remarkable that no satisfactory account has yet been given in what the bohea differs from the green tea. Dr. Cunningham, physician to the English settlement at Cimsan, and Kampfer assert, that the bohea is the leaves of the first collection.

This, however, being contrary to the general report of all travellers, that none of the first produce is brought to Europe, must be discredited; for these are all preserved for the Princes, to whom they are sold, even in China, at an immense price. Another proof is, that the boheas are brought here in the most considerable quantities, at a price greatly inferior to what even the second, third, and fourth crops are sold for in China. This not only evinces how inferior in quality the black tea must be, but also how little they are valued among those who must be acquainted with their properties.

Although the European dealers divide the green teas chiefly into three sorts, and the boheas into five, yet it is unknown from what province they are brought, of what crop they are the produce, and to which of the Chinese sorts they belong.

Added to their abuse of preparation may be that of their package. It is impossible but to know that their bad qualities must be considerably augmented by being so closely packed, for such a length of time, in such slight wooden chests, lined with a composition of wood and lead. Considerable quantities are likewise damaged by salt water and other causes, which, by the management of the tea dealers, are mostly mixed, and sold under different denominations. How the tea must be affected by the corrosion of the lead and tin by the marine acid, those of the least chemical knowledge will easily determine. To what danger must, therefore, the constitution of those who are in the constant habit of drinking such an empoisoned drug be exposed, may easily be imagined. Surely, when all these circumstances are considered respecting the pernicious mode of preparation, and particularly the poisonous qualities they are also liable to contract from the nature of their package, every person must be convinced to what a loss of health, if not of life, the constant use of such teas must expose them. Such evidence of their deleterious tendency is almost sufficient to alarm mankind against so prevailing an evil, without any further arguments; but as health is too precious not to require every possible proof that can persuade us to avoid what so immediately threatens our existence, the following arguments and testimonies of the bad qualities of foreign teas must not be omitted. Previous, however, to an investigation of their effects, it may be necessary to say a few words respecting