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These terraces covered an area of about three acres, and looked like a series of cataracts changed into stone, each edge being fringed with a festoon of delicate stalactites. The water contained about eighty-five per cent. of silica, with one or two per cent of iron alumina, and a little alkali.
Why in the thousand and more observed forms of snow-crystals the filaments of ice should always be arranged at angles of 60 degrees or 120 degrees; why sulphate of potash and sulphate of alumina should crystallise in octahedrons or in cubes, but in no other forms; what is the real connection between molecular changes in the brain-substance and states of consciousness all these, and a myriad more, are unsolved mysteries: we can only say that we are dealing with facts of experience.
For instance, a sapphire is the result of the complete and perfect fulfillment of the laws of aggregation in the earth of alumina, and it is therefore beautiful; more beautiful than clay, or any other of the conditions of that earth. But a square leaf on any tree would be ugly, being a violation of the laws of growth in trees, and we ought to feel it so.
The latter substance, a silicate of alumina, is not found in England, and at but few points on the Continent. We have it in abundance and of the finest quality. The extraordinary steps made within five years in the arts of destruction were illustrated by the twelve-inch Armstrong rifles of England and the Essen gun, throwing a 1212-pound shot.
To speak first of the sandy division: beds of loose sand are frequently met with, of which the grains consist entirely of silex, which term comprehends all purely siliceous minerals, as quartz and common flint. Quartz is silex in its purest form. Flint usually contains some admixture of alumina and oxide of iron.
An English chemist reports that the South Carolina phosphate, made in factories situated in and near Charleston, ranks next in value to this Cambridge product. It contains 54 per cent. of tribasic phosphate of lime, 14 per cent. of carbonate of lime, 3-1/2 per cent. of iron oxide and alumina, 2-1/2 per cent. of fluoride of calcium, and 15 per cent. of silica.
Very many bodies, such as ruby, diamond, emerald, alumina, yttria, samaria, and a large class of earthy oxides and sulphides, phosphoresce in vacuum tubes when placed in the path of the stream of electrified molecules proceeding from the negative pole.
One of these parts is in a beaker glass over-saturated with chemically pure chloride of ammonia, whereby any iron of oxide present and a little dissolved alumina fall down as deposit. The precipitate is separated by filtering, washed, dried at 212° Fahrenheit and weighed. To the filtrate is then added a solution of oxalate of ammonia until a white precipitate of oxalate of lime is formed.
First, at least three earthy salts-the sulphates of lime, alumina, and potassa. All these exist uncombined in the gum, and free to work their will on the mucous tissues. A green extractive matter, which comes in all vegetal bodies developed under sunlight, next deserves a place by itself, because it is one of the few organic bodies of which no rational analysis has ever been pretended.
It is a remarkably excellent imitation silicate of alumina; the weight, color, and hardness, the measurements table, girdle, and culasse all correspond exactly with the original. It lacks only in density, and perhaps a trifle in but no; it would require an expert test to determine that it was not a true ruby." "Then," I eagerly pursued, "even an expert might be imposed upon by the replica?"
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