Among the minerals which contain a considerable proportion of radium we may mention a natural phosphate of uranium known as autunite, named for the town of Autun, in France, near which it has been found. This mineral has been known for a long time past, and owing to the uranium it contains has been used for some purposes. The beds of this mineral which are, found at Saint Symphorien de Marmagne, in the Seine-et-Loire district, were worked by M. de Fontenay, the director of the great Baccarat glass factories, owing to the special color which some of the crystals were found to give to the glass. The discovery of radium drew attention again to this mineral, and a new search was made to find the beds of it which had been lost. The search has been successful owing to the recent work of M. H. Marlot, and at a depth of 6 feet below ground in a special kind of marl, they found plates of autunite which reached over an inch in thickness. This mineral was found to contain a large amount of radium salts, and it acted strongly upon the photographic plate, showing that it is quite powerful in its actions. We thus have another radium-bearing mineral to add to the list. The recently-published report of the British government dealing with the fishery and hydrographical investigations in the North Sea during the years 1902-3 contains much interesting data concerning the fecundity of fish. According to the report, the turbot is one of the most prolific of sea fishes. The number of eggs in five specimens examined varied from over five millions to more than ten millions. The heaviest of these specimens weighed only 21 pounds, and the fact is expressed that large specimens are still more fertile. There is, however, but limited information extant concerning the rate of growth of turbot, but a specimen marked and put back in the sea on May 27, 1891, had grown from six to eight inches when caught again on August 31 of the same year. Unlike some round fishes, the flat species keep to the bottom of the sea and move along it, traveling great distances. Records have been obtained showing that plaice have traveled eighty-eight miles in twenty-eight days, or an average of not less than three miles a day. Experiments in the large spawning pond of the Fishery Board's laboratory at Aberdeen showed that this fish could cover more than a mile in an hour. Apparently the brill is not so fertile as the turbot. A brill weighing only SVa pounds had the comparatively trifling number of 825,-000 eggs. The halibut takes second place as to quantity, and third as to value among all the flat fishes. In a specimen weighing 91 pounds no ess than 1,327,-000 eggs were found.
Science Notes - December 9, 1905
This article was originally published with the title "Science Notes" in SA Supplements 60, 1562supp, 455 (December 1905)