M. P. de Wilde, professor at the University of Brussels, has taken up the study of the gold which is contained in sea-water. He proposes a new method of extracting it. A ton of sea water is treated with 4 or 5 cubic centimeters of an acid and concentrated solution of chloride of tin. The whole of the gold is thus concentrated in the complex body known as purple of Cassius, which contains gold, tin and oxygen. It is found that the purple body is fixed very strongly upon the flaky hydrate of magnesium which is set free in sea water when we pour in lime water. The hydrate falls to the bottom with the gold attached to it. The gold is set free by a cyanide of potassium solution (about 1 in 2,000) thus forming a cyanide of gold. The metal can then be extracted by a number of well-known methods. Liversedge shows that when sea water is sent in casks, the wood causes the gold to precipitate, and thus none is found in the water. M. de Wilde made experiments at the seashore in France on the west coast and found traces of gold in the water. He considers that much of the gold is thrown down to the sea bottom, and thus it escapes us. It will be remembered that Liversedge, professor at the University of Sydney, found from % to 1 grain of gold per ton of sea water from the coast of New South Wales. From time to time we hear of experiments made upon the effects which certain colors seem to have upon the human organism. A recent contribution to this subject comes from Prof. Redard, of Geneva, who has been making researches with a view of using the physiological effects of colored light in surgery. At the Swiss Dental Congress he described a new anes-thetic effect which is based upon the influence of the blue rays upon the nervous centers. A number of experiments showed him that he could obtain a deadening of the nerves which was sufficient to allow of making some local operations of short duration. According to Prof. Redard, each of the primary colors has a special and well-defined action on the organism. Red light is an exciting and an irritating agent. We are aware of its action in modifying the virulence of certain eruptions and how it has been applied in the variole. Yellow light seems to have a depressing action, while with blue light we obtain a sensation of calm and ease. To apply the anesthetic method with blue light, the patient is seated on a chair at 10 inches from a 15-candle-power incandescent lamp. The bulb of the lamp is of blue glass and it has a nickeled reflector. The head is covered with a thin blue veil and the patient directs his vision toward the lamp. After a few minutes the subject is found to be in an unconscious state, and on lifting up the veil we find that the pupil is dilated and the regard fixed. In this state a tooth can be extracted or other short operation carried out without pain. However, it must be understood that the effect succeeds better with some subjects than with others. Dr. Milliard, of London, used blue light for the same purpose. In twenty cases the success was complete. In eight others it did not succeed. The effect is not attributed to hypnotism, but to the direct action of the rays upon the nerve centers. Limestone Island is the center of the New Zealand cement industry. It is about 100 square miles in area, and is wholly composed of hydraulic limestones. It .was reported on originally by Sir James Hector for the New Zealand government as an island of hydraulic limestone of a quantity practically unlimited, and estimated to contain over 30.000,000 tons above water level. Beneath the limestone there is believed to be coal, and for this borings are now going on.
Science Notes - December 23, 1905
This article was originally published with the title "Science Notes" in SA Supplements 60, 1564supp, 503 (December 1905)