100 YEARS AGO

A New Mineral from Ceylon. In the beginning of February I bought from Mr. Holland 5 cwt. of the mineral described by Prof. Dunstan in last week's Nature (p. 510)... I had hoped to have positive and definite results to communicate before describing its constituents, but the publication by Prof. Dunstan of an analysis, and his statement that he is still engaged in its investigation, makes it necessary to write this letter... Fractionation shows that the oxalate precipitate (the portion soluble in ammonium oxalate) gives equivalents between 25.0 (the most insoluble portion of the double sulphate) and 44.7 (the most soluble portion); by far the major part of the element has the last mentioned equivalent... Assuming that the element is a tetrad, which is probable from its behaviour, it undoubtedly possesses an equivalent approaching the highest number (44.7), and for this there is a gap in the periodic table between cerium and thorium; one at least of the elements present (supposing that there is more than one present) will probably have an atomic weight of about 177, preceding tantalum (182.5) in the horizontal row of the periodic table... Within the limits of this letter I am obliged to omit many more characteristics of this curious ore... I regret to have been obliged to tell an imperfect story.

William Ramsay

From Nature 7 April 1904.

50 YEARS AGO

The brain mechanisms which serve the sun navigation of the animals mentioned are presumably of a similar nature in all species and are probably based on the same principles as human sun orientation. They can also be expected to share certain properties with other time-keeping mechanisms (internal clocks) which are of wide occurrence. They keep time fairly well on their own and they are set and kept in pace by light stimuli. Their metabolic nature has in certain cases been established. A third property of such systems is that they regulate motor activities. Drosophila, for example, normally emerge from their pupæ before dawn. If a bottle with larvæ and pupæ of D. melanogaster is artificially illuminated during three consecutive nights and kept in darkness during daytime, the flies which emerge during the following week will ‘remember’ the time of the artificial dawn and emerge in the evenings, even when now kept in perpetual darkness.

H. Kalmus

From Nature 10 April 1954.