This section is from the book "Meals Medicinal", by W. T. Fernie. Also available from Amazon: Meals Medicinal: With "Herbal Simples" Curative Foods From the Cook in Place of Drugs From the Chemist.
The Lichen (Cetraria Islandica), Or Iceland Moss, is now of British growth, being found especially in Wales, and Scotland, though most probably the Icelanders were the first to learn its helpful properties. In two kinds of pulmonary consumption this Moss will assist to promote a cure, - that with active bleeding from the lungs, and that with profuse purulent expectoration. The Icelanders boil the Moss in broth, or dry it in cakes, which are used as bread; they likewise make a gruel of it, but the first decoction in boiling water being purgative, is thrown away. An ounce of the Iceland Moss boiled for a quarter of an hour in a pint of milk, or water, will yield seven ounces of thick mucilage, which is found also of much use against dysentery. Contained in the Moss are cetrarin, uncrystallizable sugar, gum, and green wax, with phosphate of lime, and potash. The Moss, again, affords benefit in diabetes, and for general atrophy. Francatelli directs for making Iceland Moss Jelly: "Boil four ounces of the Moss in one ounce of water; then add the juice of two lemons, and a bit of the rind, with four ounces of sugar, (and perhaps a gill, or half pint of sherry); boil up, and remove the scum from the surface; strain the jelly through a muslin bag into a basin, and set it aside to become cold, but it is more efficacious when eaten warm." This Moss also includes chemically "lichenin," and "iso-lichenin," which is a soluble sort of starch.
Dr. Hutchison concludes that its nutritive value is nil. For making a "Brawn of Iceland Moss": "Stew two handfuls of Iceland Moss several times in scalding water; add one pint of water, and let it boil for some minutes; then pour off this bitter-tasting water, and add fresh water (a pint), and let it boil for half an hour until the decoction has been reduced to half the quantity, and on cooling becomes a jelly; next strain the decoction, and boil it again with white sugar-candy until all is dissolved; clear it like brawn with half the white of an egg; strain it again through a napkin into a dish, and put it in a cold place so that it may set. Take a teaspoonful frequently. Where heartburn occurs leave the sugar out".
Irish Moss (Carrageen) is collected chiefly on the northwestern shores of Ireland, also on our English rocky coasts, and some in Hamburg. Its chief constituent is a sort of mucilage which dissolves to a stiff paste in boiling water, this containing some iodine, and much sulphur. The Moss needs soaking for an hour or more in cold water, before being boiled for use in water, or milk. It contains starchy, heat-giving nourishment, about six parts thereof to one of flesh-forming food, whereby its jelly is found to be specially sustaining to persons suffering from pulmonary consumption, with an excessive hectic waste of bodily heat. The botanical name of this Moss is Ckondrus crispus, and it varies much in size, and colour. At one time its cost was half-a-crown for a pound. Whilst growing in small pools it is shallow, pale, and stunted; but when found at the bottom of a deep pool, or under the shadow of a big rock, it occurs in dense masses of rich ruddy purple, with reddish-green thick fronds. The Moss always needs to remain well washed by the tide. It is very wholesome for gouty persons, and for those who are prohibited from eating starchy foods, as it contains neither sugar, nor starch, but a large amount of gelatinous, and mineral matter.
It may be cooked as blancmange, or baked with milk as a pudding, being sweetened with sugar, and flavoured with lemon-rind, ratafia, etc. The iodine in its composition is of use for chronic sore throat, whilst the Moss is medicinally demulcent.
"That throat so vex'd by cackle, and by cup; Where wine descends, and endless words come up: Much injur'd Organ!"