Science Sittings

New Zealand Tablet, 17 December 1908, Page 35

Science Sittings

by « volt

Coldness of Ice.

It seems strange to think that some ice is colder than other ice. The term ' ice cold ' always seems to signify a definite temperature. All water under similar conditions freezes at a certain definite temperature. But when the thermometer falls below that it continues to affect the ice, making it harder and colder. The test has been made by placing a piece of ice from the north and a piece of ice formed in the south near a stove together. The former took much longer to melt than the latter. Carbon the Main Constituent of Plant and Animal. The all-pervading element of life is carbon. It is the element in nature on which the life of every living thing whether plant or animal, depends. The work we do, indeed, every movement we make, is the result of energy stored up in the organism, the energy being proportionate to the amount of carbon consumed. In its free state, carbon forms charcoal, coke, black lead, and diamond. In its combined state it is a necessary part of the flesh, blood bone, and muscle. Carbon is the main constituent of plants, its percentage in wood exceeding that of the other elements of which wood is built ; and it is also the constant component of the atmosphere, where it exists as carbonic acid gas. There is practically no limit to its sway. It is found in the stars and in almost every sample of water. The earth's crust contains vast quantities of it in chalk* limestone, and marble. Such diverse substances as explosives, dyes, fuel, foods, liquors, clothes, drugs, and printer's ink; the evil smells that arise from putrefaction and the odors of the most fragrant perfumes are all compounds of carbon, the element of life. The compounds of carbon number at least 60,000, the cause of their multiplicity being found m a peculiar property of carbon itself. Its atom is a wanderer. While other atoms usually are unwilling to combine even with those of their own kind, the carbon atom journeys far afield, uniting not only with itself but other elements in endless different proportions. '

Some Queer Trees.

The breadfruit tree of Ceylon is very remarkable. Its fruit is baked and eaten as we eat bread, and is equally good and nutritious. In Barbutu, South America, is a tree winch, by piercing the trunk, produces milk with which the inhabitants feed their children. In the interior of Africa is a tree which produces excellent butter. It resembles the American oak, and its fruit from which the butter is prepared, is not unlike the olive. Park the great traveller, declared that the butter surpassed' any made in England from cow's milk. At Sierra Leone is the cream fruit tree, the fruit of which is auite agreeable m taste. At Table Bay, near the Cape of Good Hope, is a small tree the berries of which make excellent candles It is also found in the Azores. The vegetable tallow tree also grows m Sumatra, in Algeria, and in China. In the island of Chusan large quantities of oil and tallow are extracted from its fruit, which is gathered in November or December, when the tree has lost all its leaves. The bark of a tree in China produces a beautiful soap. Trees of the sapindus or soap berry order also grow in the north of Africa. They are amazingly prolific, and their fruit contains about 38 per cent, of saponin.

An Island in the Air.

Three miles south of the Mesa Encantada, in Mexico is a splendid specimen of fantastic erosion — an ' island ' in the air, a rock with overhanging sides nearly 400 feet high 70 acres in area on the fairly level top, indented with countl less great bays, notched with dizzy chasms. The greater part of the island overhangs the sea like a huge mushroom, and on the top stands a town which for artistic charm,' ethnological interest, and romantic history has no peer! This little town of Ancoma is one of the most perfect types of the prehistoric pueblo architecture. Most of the houses remain of the type invented when every house must be a fort. One climbed a ladder to his first floor and nulled up the ladder at night, living on the second and third floors and using the ground floor as a cellar. Against enemies armed only with bows and arrows this was a fair defence. Comfort had to be sacrificed to safety. Nothing except the eagle sought such inaccessible eyries as these victims of their own civilisation. Because they were farmers instead of freebooters, because they had homes instead of being vagrants they were easy to find, and they were the prey of a hundred nomad tribes. With inconceivable labor this island town in the air was built and fortified. It was reached only by a mere trail of toe holes up the stem of the 'mushroom.' The age of the island is not known except that it was already old in 1540, when the first explorer visited it and wrote an account of its wonders.