Cold water removes the mucilage, which, after due concentration, may be precipitated by neutral acetate of lead. This mucilage, when boiled for some time with nitric acid, produces oxalic acid and microscopic crystals of mucic acid (beautifully seen by polarized light), soluble in boiling water and precipitating on cooling. With one part of the drug and 100 parts of boiling water a thick liquid is obtained which affords transparent precipitates with neutral acetate of lead or alcohol, in the same way as carrageen. With 50 parts of water, a transparent tasteless jelly, devoid of viscosity, is produced; in common with the mucilage, it furnishes mucic acid, if treated with nitric acid. Micro-chemical tests do not manifest albuminous matter in this plant.
Some chemists have regarded the jelly extracted by boiling water as identical with pectin, but the fact requires proof. Payen[2782] called it Gelose, and found it composed of carbon 42·77, hydrogen 5·77, and oxygen 51·45 per cent. Gum Arabic contains carbon 42·12, hydrogen 6·41, and oxygen 51·47 = C₁₂H₂₂O₁₁. Payen’s gelose imparts a gelatinous consistence to 500 parts of water; it is extracted by boiling water from the plant previously exhausted by cold water slightly acidulated.[2783]
The inorganic salts of Ceylon moss consist, according to O’Shaughnessy, of sulphates, phosphates, and chlorides of sodium and calcium, with neither iodide nor bromide. Dried at 100° C., it yielded us 9·15 per cent. of ash.
Uses—A decoction of Ceylon moss made palatable by sugar and aromatics, has been recommended as a demulcent, and a light article of food for invalids. In the Indian Archipelago and in China, immense quantities of this and of some other species of seaweed[2784] are used for making jelly and for other purposes.
APPENDIX.
SHORT BIOGRAPHIC AND BIBLIOGRAPHIC NOTES,
Relating to Authors and Books quoted in the Pharmacographia. They may be completed by consulting especially the following works:—
Choulant, Geschichte und Literatur der älteren Medicin, Part I., Bücherkunde für die ältere Medicin. 1841.
Kopp, Geschichte der Chemie, 4 vols., 1843-1847.
Meyer, Geschichte der Botanik, 4 vols., 1854-1857.