This section is from the book "A Treatise On Therapeutics, And Pharmacology Or Materia Medica Vol2", by George B. Wood. Also available from Amazon: Part 1 and Part 2.
It is scarcely necessary to state that this is the product of the common fax plant, or Linum usitatissimum. The appearance of the seeds is too well known to require description. I shall content myself with calling attention to the properties which render them valuable as a medicine.
The seeds of flax contain, in their investing coat, a large quantity of mucilaginous matter, which is imperfectly extracted by cold, but readily and abundantly by hot water, forming a thick mucilage. When this is evaporated to dryness, the residue is found to consist of a portion soluble in water, which is probably gum, and another insoluble, but swelling up and softening like the insoluble matter of tragacanth. The mucilage, therefore, is an imperfect solution, holding part of the gummy matter in suspension.
Besides this mucilaginous matter in the coating, there is in the interior of the seeds a large proportion of fixed oil, which may be obtained by expression, and which gives valuable emollient properties to the powder of the seeds. (See Emollients.) it is the mucilage which imparts its demulcent virtues to flaxseed, and which, in preparing the medicine for use in this capacity, it is always desirable to obtain separate from the oleaginous ingredient.
Uses as a Demulcent. As a demulcent, flaxseed is used exclusively in the form of infusion. it has the general character of the class in a high degree, and is very much employed. For external use, one of the medicines, hereafter to be considered, is generally preferred; but internally the infusion of flaxseed is largely prescribed. The complaints in which it is most frequently administered are catarrhal affections, enteritis, dysentery, and inflammation or irritation of the kidneys and urinary passages, including of course strangury. it is also frequently injected into the bowels, in irritated states of the rectal mucous membrane. in irritable conditions of the stomach, it is inferior to gum arabic, as less delicate, and usually less acceptable. it is often flavoured with sugar and lemon-juice, or with liquorice, and, when used in bronchial inflammation, as in ordinary colds of the chest, measles, etc., it is very advantageously associated with tartar emetic. in many cases of catarrh, nothing more is necessary than to give the patient daily, in small quantities at a time, frequently repeated, a pint or more of flaxseed tea, with one or two fluidrachms of antimonial wine in each pint.
The infusion may be made in the proportion of half an ounce of the seeds to a pint of boiling water. The seeds should not be bruised, and decoction should be avoided, as otherwise the oil might be extracted, and render the infusion less agreeable, and less acceptable to the stomach. The infusion, made with a smaller proportion of the seeds, may be used as a mucilaginous bath in cutaneous affections, extending largely over the body, and attended with much irritation, as urticaria, lichen, psoriasis, etc. Though probably not so much used externally as the infusion of slippery elm bark, it has the advantage over that demulcent, of not being precipitable by solution of acetate of lead, in such a degree as to be incompatible with their simultaneous use. When, therefore, it may be desired to combine a demulcent with a saturnine solution, flaxseed should be resorted to preferably to the bark just mentioned. it is incompatible with the solution of subacetate of lead.
Compound infusion of Flaxseed (infusum Lini Compositum, U. S.; infusum Lini, Br.) is prepared, according to the U. S. Pharmacopoeia, by infusing half a troyounce of the seeds, and two drachms of bruised liquorice root, in a pint of boiling water, and straining. A pint or more may be taken in twenty-four hours.