Decembee 4, 1908] 



SCIENCE 



805 



icist, and the electric furnace of the chemist 

 are of almost equal importance with the tele- 

 scope. 



Professor Hale, in this most interesting 

 volume, describes the new type of observatory 

 and explains the work of a modern astronomer 

 and the problems which confront him. From 

 his great experience in designing and equip- 

 ping two great modern institutions of astro- 

 nomical research — the Yerkes and the Mount 

 Wilson observatories — Professor Hale has 

 drawn freely for concrete illustrations of the 

 difficulties which confront the student of 

 stellar evolution. He shows how the feeble 

 rays of light from a scarcely visible star are 

 gathered together by the giant lens or mirror 

 of the telescope and brought into a physical 

 laboratory, where they are analyzed by the 

 spectroscope, and forced to reveal the secret of 

 the star's evolution. 



The book is essentially a popular treatise; 

 it was planned as a handbook to the Yerkes 

 Observatory. It is non-technical, readable 

 and gives a clear explanation of the purposes 

 and observational methods employed by the 

 author in his notable researches upon the sun 

 and the chemistry of the stars. The book is 

 discursive, however: the problems are treated 

 individually, without showing clearly their in- 

 terrelation and their bearing upon the general 

 problem of stellar evolution. But the work 

 was not intended as a scientific presentation 

 of the subject; it was planned for the general 

 reader, not for the investigator. The illus- 

 trations, from photographs taken principally at 

 the Yerkes and Mt. Wilson observatories, are 

 very beautiful, but are, if anything, rather 

 too numerous. 



Charles Lane Poor 



ACTION OF THE RADIUM EMANATION ON 

 SOLUTIONS OF COPPER SALTS'" 

 A year ago Messrs. Eamsay and Cameron 

 announced in several journals that they had 

 observed the formation of the alkali metals 

 and of lithium in solutions of copper salts 

 ■which had been subjected to the action of the 



^Translated from the paper by Mme. Curie and 

 Mile. Gleditsch, Comptes retidus, 147, 345 (1908). 



radium emanation. They concluded that the 

 metal copper was degraded, in the presence of 

 the emanation, into elements of the same 

 series having lower atomic weights : potas- 

 sium, sodium, lithium.' 



These important results attracted a great 

 deal of attention and it seemed desirable to 

 repeat the. experiment in laboratories possess- 

 ing a suificient quantity of radium. The ex- 

 periment to be repeated was as follows. A 

 solution of a copper salt (sulphate or nitrate) 

 was placed in a small glass flask into which 

 was introduced a large amount of the emana- 

 tion and this was allowed to decay spon- 

 taneously. The copper was then removed, the 

 resulting solution was evaporated to dryness, 

 and the residue examined. The same pro- 

 cesses were performed with a solution of the 

 same copper salt which had not been subjected 

 to the action of the emanation. The experi- 

 ments were repeated several times. The resi- 

 due consisted chieily of sodium salt (with a 

 small amount of potassium and calcium). In 

 the four experiments described, in which the 

 emanation acted, lithium was detected by 

 means of the spectroscope. In the blanli ex- 

 periments there was much less residue and 

 the presence of lithium could not be detected. 

 Messrs. Ramsay and Cameron made one ex- 

 periment to determine the quantity of lithium 

 observed and they estimate the presence of 

 about 0.00017 milligram in the residue which 

 weighed 1.67 milligTams, the amount of copper 

 taken being 0.27 g. (0.815 g. copper nitrate). 

 In the corresponding blank experiment the 

 residue was only 0.79 milligrams.^ 



We have tried to reproduce the results under 

 conditions as free from error as possible. The 

 experiment is a delicate one and there are 

 several sources of error, chief among them 

 being the use of a glass vessel as Mr. Ramsay 

 himself remarks. 



"" Nature, July, 1907; Jour. Chem. Soc, Sep- 

 tember, 1907; Comptes rendus, 1908; Archives de 

 Oenive, April, 1908; etc. 



^This quantity of metallic lithium does not 

 check with the value indicated by the mixture of 

 sodium and lithium salts which was taken as a 

 comparison. There must be some error of cal- 

 culation which we have not been able to locate. 



