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The price of kelp in the market fluctuates according to thedemand ; but the quality is very different, and the best alwaysobtains the highest price. That produced from Staffa , and someother places, and prepared with more than ordinary care, hasbeen occasionally sold at 20/. per ton, while inferior kinds havescarcely brought 61. Supposing the average price, therefore, tobe 12/., the annual produce will amount to 120,000/.; and, cal-culating the expense at one-third, 80,000/. will remain as the pro-fit of this manufacture.
2. Soda. —This alkali is obtained from the ashes of severalkinds of marine vegetables, and is extracted from Barilla andKelp.
Soda was first made in Scotland at the village of Dalmuir, inDumbartonshire, and afterwards at Rutherglen Bridge, PortDundas, Camlachie and Govan, near Glasgow ; and at Leith,Queensferry, Greenock , and at different places in Ayrshire ; butmany of the works have been given up in consequence of thefailure of demand for this article.
Soda is used by Turkey-red dyers, and in washing clothes;and, lately, in making Soda Water. This salubrious beverage ismade at Edinburgh, Glasgow, Greenock , and at several otherparts. It is merely a solution of soda in water, strongly impreg-nated with carbonic acid gas ; and is used as a substitute for thewaters of Spa, Seltzaer, or Pyrmont.
3. Muriat of Ammonia, or Sal-Ammoniac _This salt is made
from animal substances, as bones, horns, hoofs, <Src. and also fromsoot. Some years ago, there were several works for the manufac-ture of this article at Edinburgh and Glasgow ; but the only onenow carrying on to any extent in Scotland , is at Borrowstoun-ness. This salt is used by dyers, and very extensively by work-ers in metal, particularly in the process of tinning cast-iron cu-linary utensils. The price of sal-ammoniac is at present about91. 10s. per cwt.
4. Sidphat of Soda, or Glauber's Salt. —This article is used inmedicine; and is made at Edinburgh, Glasgow , and several otherplaces, from the residuum in the retorts when muriatic acid isdistilled.
5. Epsom Salt and Magnesia. —These articles are made atSaltcoats, and in the neighbourhood of Edinburgh , from thatportion of the concentrated sea-water of the salt-pans which docsnot crystallize, and remains after the salt is withdrawn.
6. Allum, or Sidphat of Alumine. —The manufacture of this saltin Scotland , commenced in 1797, at the village of Hurlet, wRenfrewshire ; and other works, on a more extensive scale, wereestablished in 1808, at Campsie, in Stirlingshire, by the samecompany. At both these works, 100 persons are employed, whoreceive each from 2s. to 3s. 6d. per day of wages. From 7000to 8000 tons of coals are used annually; and the produce is about