Adqcst 6, 1909] 



SCIENCE 



171 



reservoirs and dams to imponnd water for 

 purposes of irrigation. These waters are 

 often strongly alkaline, and affect the con- 

 crete of the dams most injuriously. To 

 avoid this evil is one of the important prob- 

 lems now in hand. 



One laboratory of the technologic branch 

 is in "Washing-ton, and its particular func- 

 tion is to examine the coal purchased for 

 the use of the government, and also to pass 

 upon the quality of the structural materials 

 used in public works. This latter heading 

 covers not only siibstances like cement, 

 plaster, clay, brick and terra eotta, but also 

 iron and steel, mineral paints, and roofing 

 materials, whether of metal or of asphalt. 

 In short, this laboratory is entirely tech- 

 nologic in character, and its chemists find 

 their time, fully occupied with routine 

 affairs. 



Although petroleum is studied by the 

 technologic branch with reference to its 

 efSciency as fuel ; still other investigations 

 upon it are carried on in a distinct labora- 

 tory under Dr. David T. Day. Dr. Day is 

 engaged upon a systematic study of all the 

 petroleum fields of the United States, de- 

 termining the physical properties of the 

 oils and examining their distillation prod- 

 ucts. In each oil he determines sulphur, 

 asphaltum, paraffin, water and the unsat- 

 urated hydrocarbons, and when this pre- 

 liminary investigation is finished the work 

 wiU be further developed with regard to 

 special details. It is proposed also to re- 

 examine the oils from time to time, in order 

 to ascertain whether the wells have under- 

 gone any change in character. In this 

 work Dr. Day cooperates with a committee 

 of the International Congress on Petroleum, 

 for the purpose of establishing uniform and 

 trustworthy methods of research. Dr. Day 

 has also, for several years, been studying 

 the filtration of petroleum through clays 

 and shales, in which he finds that a frac- 



tionation is effected similar to that pro- 

 duced by distillation. This work is be- 

 ing continued, and is yielding interesting 

 results. 



F. W. Clarke 

 U. S. Geological Survey 



THE POPULATION OF FRANCE 



1^ view of the interest in the thirteenth 

 census of the United States for 1910, of which 

 the law governing the enumeration has just 

 been passed, the readers of Science may be 

 interested in the report of the chief of gen- 

 eral statistics of the movement of population 

 in France, during the year 1908, as given in 

 the Journal Official. This is all the more in- 

 teresting because of the views entertained in 

 some quarters that France should be num- 

 bered among the so-called decadent peoples. 

 The figures for 1908, however, show that the 

 excess of births over deaths, based upon an 

 enumeration of 315,928 marriages, amounts to 

 46,441. The corresponding figure for the ten 

 years ending with 1907 was 40,550. The fol- 

 lowing table gives the comparative returns for 

 the decade, with which 1908 is compared : 



Mar- 

 riages 



Births Deaths 



1898 1 287,179 843,933 810,073 23,860 



1899 1295,752 847,627 816,233 31,394 



1900 1299,084 827,297j853,285' 



1901 1.303,469 857,274;784,876| 72, 



1902 : 294, 786 845, 378 '76 1,434 8.3,944 



1903 i --95,996 826,71275.3,606, 73,106 



1904 : 298,721 J818,229 761,203. 57,026 

 19i»5 i302,623;807,291;770,171: 37,120 



1906 ,306,487:806,847 780,196 26,651 



1907 1314,7.56 1773,64579.3, •'■.37| 



Av. 1898-1907' 299,885 182.5,423 788, 461 40,550 

 315,928 1791, 712,745,271 46,441 



1908 



19,892 



4,588 



It is noteworthy that for 1908 the number 

 of deaths was the smallest in eleven years and 

 considerably smaller, of course, than the 

 average for ten preceding years. In births 

 there is a recovery from the minimum of 

 1907, and marriages are the largest in eleven 

 years, being five per cent, greater than the 



