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Page:Popular Science Monthly Volume 56.djvu/522

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sented as nearly as practicable the conditions existing in the actual use of steam pipes. Of sixteen non-conducting preparations tried, the most efficient were found to be those made of cork; next was a cover composed of an inner jacket of earthy material and an outer jacket of wool felt; and next magnesia. In reference to the last substance it is, however, observed that, while it is a most effective non-conductor, the name has been applied to many compounds of which the greater part consist of carbonate of lime or plaster of Paris, materials which are not good as heat retardents. Asbestos is merely a non-combustible material in which air may be entrapped, but, when non-porous, is a good conductor of heat. Generally speaking, a cover saves heat enough to pay for itself in a little less than a year at three hundred and ten ten-hour days, and in about four months at three hundred and sixty-five twenty-four-hour days. The decision as to the choice of cover must, however, come from other considerations, as well as from that of non-conductivity. Ability to withstand the action of heat for a prolonged period without being destroyed or rendered less efficient is of vital importance. The cork coverings were found to respond to this test extremely well, and there can be no question respecting magnesia; but Mr. Norton does not consider it safe to put upon a steam pipe wool, hair, felt, or woolen felt in any form, though the danger is not likely to accrue when an inch of fireproof material stands between the felt and the pipe. In general it may be said that if five years is the life of a cover, one inch is the most economical thickness, while a cover which has a life of ten years may to advantage be made two inches thick. The method of judging a pipe cover by the warmth felt on putting the hand upon it is fallacious; the sensation depends so much upon the nature of the surface that it utterly fails to give any idea of the actual temperature.


Effect of Sea Water on Soil.—In a paper read at the British Association, 1899, on the chemical effect of the salts of the salt-water flood of November 27, 1897, on the east coast of England, Messrs. T. S. Dymond and F. Hughes recorded the remarkable result that, although the proportion of salt left in the soil was insufficient to prove injurious to growing crops, the earthworms were entirely removed, with the consequence that very few crops were worth harvesting the following year. In the next year nine tenths of the salt at first present had disappeared from the soil, and young worms had again made their appearance, but still the condition of the soil remained unsatisfactory, the rate of percolation of water through the flooded earth being only one half as rapid as through the unflooded. The authors ascribe this to the action of the chlorides of the sea water on the silicates of the soil with the formation of silicate of alumina in a gelatinous condition.


The War against Monopolies.—Mr. Robert Ewen writes, in the Westminster Review, demanding free bank circulation as likely to be a very effective weapon to be used in "the coming contest with monopolists." The subject seems to have attracted official attention in England in 1875, when Sir Stafford Northcote was Chancellor of the Exchequer. As chairman of the committee appointed to inquire into the working of the Bank Acts, he submitted a memorandum showing that, while certain items of the monopoly enjoyed by the Bank of England had been withdrawn, a residuum of restrictions on issuing banks still remained unrepealed. Some other countries have found a way of giving elasticity to the currency by buying in and laying aside their bonds, as the United States has recently been doing. This can not be done in Great Britain, because the Bank of England and the other bank monopolists block the way. The bank is tied down by acts of Parliament to buy and sell gold at a fixed price, and this restriction has been a cause of panics, whereas had gold been allowed to rise and fall in price, according to supply and demand, and the bank got a free hand in dealing with that commodity and in issuing legal notes to supply the circulating medium, "all would have gone well." Foreign protectionists now have the power to prevent British goods from getting into their markets by imposing heavy duties on them, and at the same time forcing their produce into British markets, be-