KELP is the produce of the burning of certain Fuel, as particularly specified under that article, and rendered use ful in the arts, by the quantity of soda and of neutral salts which it contains, being in the form of greenish or blueish masses approaching to black. It has become an object of great attention to individuals, from the value which the manufacture of it adds to those landed estates Which have any great extent of sea shore adapted to the raising of the loci ; and by public bodies, especially the Highland So ciety of Scotland, it is cherished as an important internal resource, by which the wealth of the country is extended. This active body has made many laudable exertions for dis covering the means of cultivating it to advantage, and of turning it to account in the other manufactures to which it is applied. In the first volume of their prize essays and transactions, We have, from the late Dr. Walker, an excel lent account of the manufacture, in the state in which it ex isted at the time when the essay was written ; together with valuable suggestions for improving its quality, and for en larging the manufacture, by the cultivation of sea-weeds. Wc have also the subsequent extended observations of his successor, Professor Jameson, which were first published in his account of the mineralogy of the Scottish isles. Con siderable precautions are required, both in the gathering, drying, and bur ning of the foci, in the treatment of the ashes, in their fusion, and the degree of exposure to the air during these processes, as the alkali is apt to be dissipated, by neglect or excess, in a variety of particulars. A know. ledge of the most advantageous process in burr is still a desideratum ; and. at the present moment, (1818 ) the Highland Society holds out the promise of an honourable testimony of its approbation, to dn. author of the best satis factory experimental account of that subject.
Till very lately, it seemed a matter of difficulty among manufacturers who purchase kelp. to assure themselves of the comparative value of different cargoes. The processes of chemists for estimating the amount of alkali contained in it had been various, and some of them appeared to imply a degree of trouble in the manipulation, which was too incon venient, and perhaps too uncertain, for habitual application to mercantile use To remove this disadvantage, was one object with the Highland Society, for which they offered two of their prizes. In consequence of which, we have two judicious essays on the subject, both deemed worthy of the proffered mark of encouragement, one by Dr. Pyle,
and another by Mr. Parkes. The first of these is most ex tensive in its objects, and in a form best adapted to direct application to practice. Meritorious new discoveries are sometimes inferior, in utility, to the w ell executed task of rendering those available which are already made, pointing out the most judicious choice among many proposed expe dients, and removing from the minds of those concerned all discouraging impressions or the difficulty of the subject. This essay has for one chief object the comparison of kelp and barilla ; an important problem, as leading us to dis cover how far the domestic kills short of the foreign article, and what hope may be encouraged of rivalling the latter in the market, without the aid of the questionable policy of a heavy duty, tending to exclude front our manufactures the employment of the cheapest article. We shall follow the order in which the subject is treated in the essay now men tioned.
The soluble part of any fair sample of kelp is separated by boiling it in water, after it. has been duly comminnted. The proportion of it that was found in the experiments of Dr. Fyfe varied from about one-third to two-thirds of the whole. The constituent parts of it are ascertained by two different processes ; the one consists in the application of the different chemical tests to the whole in a state of solu tion, the other in making it yield its saline ingredients in a crystallized form, by the process of evaporation. The et fects produced on the vegetable colours show the presence of an alkali, either uncombined, or in union only with the carbonic acid. This is well known to be soda. A quantity of potassa likewise exists in it, and spews itself, by giving, with tartaric acid a precipitate, n hich is soluble in the mu riatic acid. There is no neutral salt with an earthy or me tallic base. The existence of such a compound is excluded by the superabundance of free alkali, and this absence is confirmed by the employment of the tests, by which such base would be detected. The presence of sulpruric arid is shown, by a precipitate formed with the muriate of bary ta, and which is not soluble in muriatic acid. The pre sence of nuiriatic acid is shown, by the insoluble precipi tate the muriate of silver formed when it is treated with nitrate of silver. Other experiments were made, by which the following ingredients, besides the alkali, were found to be contained in 100 grains of the saline matter.