November 28, 1919] 



SCIENCE 



501 



DISCUSSION AND CORRESPONDENCE 



ATMOSPHERIC POLLUTION! 



The Advisory Committee on Atmospheric 

 Pollution lias published its fourth report sum- 

 ming up the observations in the year 1917- 

 1918. 



The full lists showing in detail the monthly 

 deposit figures at various stations are not 

 reproduced, inasmuch as these have been al- 

 ready published in the Lancet; but full re- 

 turns from two stations, Newcastle and Mal- 

 vern, are given;' and these give the highest 

 and lowest deposits. 



Figures of total solids deposited monthly 

 are given for all stations, 24 in number, the 

 months being on a thirty-day basis. 



In many instances the rainfall as measured 

 at these stations did not agree with the 

 amount obtained by the oiScial Meteorological 

 OfBce gauges but this is easily explained when 

 it is remembered that the gauges of the com- 

 mittee are often on roofs and are thus 

 elevated. The rainfall is given in millimeters, 

 and it would be well if we in the United 

 States would follow this example. 



At a given London station the data for the 

 half year, October to March, 1917-1918, were : 



, Eamfall 43 mm.; tar 0.14 metric ton. per 

 square kilometer; carbonaceous matter other tlian 

 tar 2.18 tons; insoluble ash 3.50; soluble ash 4.15; 

 or total solids 11.41 tons. . Of the soluble matter 

 there were 1.46 tons of sulphate, 0.63 tons of 

 chlorine, and 0.05 of ammonia. 



ISTo relationship can be discovered between 

 the deposit of insoluble matter and the 

 amount of rainfall. With the soluble matter, 

 however, it is different, and in general it may 

 be said to vary directly as the rainfall. The 

 relation may be roughly expressed by the 

 formula, <Sf = 0.058 R + 2.5, where B is the 

 rainfall in mm. and 8 the deposit of soluble 

 matter in tons per square kilometer. It is 

 not suggested that this expression can be used 

 to find the soluble deposit when the rainfall 

 is known but gives only the general nature of 

 the relationship. 



1 Meteorological Office. Report on Observations 

 1917-18. Advisory Committee on Atmospheric 

 Pollution, London, 1919. 



The report also contains the results of an- 

 alysis of the rainfall at Georgetown, British 

 Guiana, the nearest land in the direction of 

 the prevailing east-northeast trade winds be- 

 ing the shore of Morocco, distant 3,000 

 nautical miles. There can be little doubt 

 that the solids contained in the rain waters 

 collected are those normal to the rains of the 

 trade winds, with perhaps some derived from 

 the coastal sea-spray. 



The average results over the two years 1916 

 and 1917 were as follows: 



Solids In 

 Solution, 

 mg./Utre 



Oa 7.95 



Mg 3.44 



E 2.77 



Na 16.36 



ALOs 0.58 



PeA 1.97 



SiO, 0.20 



CI, 33.93 



SO. 12.02 



CO3 9.78 



NO3 11.57 



NHj 0.12 



100769 



It is shown that 55 per cent, of the solids 

 in solution in the rainfall are cyclic sea salts, 

 while 45 per cent, must have been derived 

 from atmospheric sources. 



The report also contains an account of 

 certain experiments made to determine the 

 best method of measuring continuously the 

 suspended impurity in the air. A. M. 



CAROTINOIDS AS FAT-SOLUBLE VITAMINE 



My attention has been called to Steenboek's 

 interesting observation, in Science of October 

 10, that yellow corn and the colored roots, 

 such as carrots and sweet potatoes, are richer 

 in fat-soluble vitamine than white corn and 

 the pigmentless roots and tubers. A number 

 of other instances are noted in which fat- 

 soluble vitamine and carotinoid pigment oc- 

 cur simultaneously. The fact that these rela- 

 tions have led Steenbock to the provisional 

 assumption that the fat-soluble vitamine is 

 one of the carotinoid pigments has prompted 

 me to call attention to a number of eases 

 where this relation apparently breaks down. 



