VOL.2. NO. 7
ABSTRACTS
Properties of New Elements Predicted before Diswverg. The new elementq marurium and rhenium, discove;ed by Dr. Walter Noddack in Berlin, were brought to light as a result of a law discovered by Henry G. 1. Moreley, 1 young British scientist who Lost his life in Gdlipoli during the war. When a beam of X-rays is refleefed by a crystal or powdcred crystals it is .,,read out into a band, after the manner of a beam of light paasing through a glass prism. n this band is &owed t o fa11in a photogmphic plate, a aeries of light and dark lines is obtained, which b called the X-ray spectrum. The X-rays have very short wave leneth. and therefore mme at t h e extreme and of the spectrum, beyond the ultrl-violet waves. After a study of. the X-ray spectra of many elements, Mmeley fmmulated a law which now bears hie name, by means of which, if the atomic number of an element, or it$ position in the periodic table, is known, the character of its X-ray spectrum may be obtained. A few vacancies still &st in the 92 spaces of the table, ~
617
but the characteristic spectra of the unknown element^ can be calculated in advance, and when a substance is found t o give this spectrum, there i$ no doubt of its identity. Similar methods were used in 1922 by G. Hevesy and D. coster st the Institute for Thearetical Phyricp a t Copenhagen, to dineover the missing element number 72, which was named Hafnium, after the Latin name for c o -
~enha~en. with the d i ~ m v ~ of r y the new elements, there are only three v a u n t plarrn left in the periodic system, which have the numbera 61. 85. and 87. These. like masurium and rhenium. which arc numbers 43 and 75, are odd numbers, as i t is a cvrioun fact, pointed out b y Professor Hark'ms of the University of Chicago, that in the c ~
of elements of high atomic weights, those of even n u m b u are more common. Noddaelr was trained nnder Nernst, the famous physical chemkt 01 the University of Berlin.-
Science Snoicc.
e
