_Prop., Uses, &c._ None of the Algæ are poisonous. Several are nutritious, emollient, and demulcent, from containing mucilage (carrageenin), starch, sugar (mannite), and a little albumen; and are hence used as esculents. The ash from the dried weed varies in different varieties from 9% to fully 25%; and contains variable quantities of potassa, soda, lime, magnesia, iron, manganese, and silica, with sulphuric acid, phosphoric acid, chlorine, and a little iodine and bromine. (Schweitzer; Forchhammer; Gödechens.) Sea-weeds, their charcoal, and their ashes, have been long regarded as alterative and resolvent; and anti-phthisic virtues have been attributed to them by Laennec and others. They were formerly much given in scrofulous affections and glandular enlargements; but their use is now almost superseded by that of iodine and its preparations. Dr Stenhouse has proposed some of the algæ as furnishing an economical source of mannite. The sea algæ are used for manure; their ashes form KELP. The following table, showing the results of several analyses of different kinds of algæ, and illustrating the very large amount of nitrogen contained in them, is from Mr Walter Blyth’s excellent dictionary of ‘Hygiene and Public Health.’ -----------------------------+--------+-----------+-----------+------------ | | | Per cent. | Protein Kinds of Algæ. | Water. |Dry matter.|Nitrogen in|contained in | | |dry matter.|dry matter. -----------------------------+--------+-----------+-----------+------------ _Chondrus crispus_, | 17·92 | 82·08 | 1·534 | 9·587 bleached, from Bewlay | | | | Evans. | | | | _Chondrus crispus_, | 21·47 | 78·53 | 2·142 | 13·387 unbleached, Ballycastle. | | | | _Gigastina mamillosa_, | 21·55 | 78·45 | 2·198 | 13·737 Ballycastle. | | | | _Chondrus crispus_, | 19·79 | 80·21 | 1·485 | 9·281 bleached, second | | | | experiment. | | | | _Chondrus crispus_, | 19·96 | 80·04 | 2·510 | 15·687 unbleached second | | | | experiment. | | | | _Laminaria digitata_, or | 21·38 | 78·62 | 1·588 | 9·925 dulse tangle. | | | | _Rhodomenia palmata._ | 16·56 | 83·44 | 3·465 | 21·656 _Porphyra laciniata._ | 17·41 | 82·59 | 4·650 | 29·062 _Iridæa edulis._ | 19·61 | 80·39 | 3·088 | 19·300 _Alaria esculenta._ | 17·91 | 80·09 | 2·424 | 15·150