The experience of France ought to be a sufficient guarantee that the manufacture of beet root sugar is not a speculative but a great staple trade, in which the supply can be regulated by the demand, with a precision scarcely attainable in any other ease, and when, in addition, this demand tends rather to increase than to diminish. That the trade is profitable there can also be no doubt from the large capital embarked in it on the Continent--a capital which is steadily increasing even in France, where protection has been gradually withdrawn, and where, since 1848, it has competed upon equal terms with colonial sugars. The produce of France in 1851 was nearly 60,000 tons. The beet root sugar made in the Zollverein in 1851 was about 45,000 tons. Probably half as much more as is made in France and the Zollverein, is made in all the other parts of the Continent. In Belgium, the quantity made is said to be 7,000 tons; in Russia, 35,000; making a total of beet root sugar now manufactured in Europe of at least 150,000 and probably more, or nearly one-sixth part of the present consumption of Europe, America, and our various colonies. In 1847 this was estimated at upwards of 1,000,000 tons; and, as the production has increased considerably since that period, it is now not less than 1,100,000 tons. The soil of the Continent, it is said, will give 16 tons to the acre, and that of Ireland, 26 tons to the acre. The former yields from 6 to 7 per cent.--the latter from 7 to 8 per cent. as the extreme maximum strength of saccharine matter. The cost of the root in Ireland--for it is with that, and not with the cost of the Continental root, with which the West Indies will have to contend--is said to be at the rate of 16s. per ton this; but will probably be 13s. next season. The cost of manufacture is set down at £7 5s. per ton. Calculating the yield of the root to be 7½ lbs. to every 100 lbs., for 26 tons the yield would be nearly 2 tons of sugar, which would give about £9 10s. per ton, putting down the raw material to cost 14s, 6d. per ton, the medium between 16s. and 13s. Thus a ton of Irish-grown and manufactured beet root sugar, would cost £16 15s. per ton. Mr. Sullivan, the scientific guide to those who are undertaking to make beet root sugar at Mountmellick, Queen's County, Ireland, estimates the cost of obtaining pure sugar at from £16 17s. to £19 18s. per ton, according to the quantity of sugar in the root.