A. N. Winchell— Great Dust fall of 1920. 



355 



It is remarkable that no chemical analyses of samples 

 of American dustf alls are on record. Furthermore, anal- 

 yses of foreign dustf alls are very uncommon and several 

 of those published are too incomplete to be satisfactory 

 for comparisons or for calculations of mineral compo- 

 sition. All the other chemical analyses of foreign dust- 

 falls are assembled in the following table in which the 

 average of the analyses of the Madison dustfall is 

 included for convenience. 



Table II 



. — Analyses of fot 



-eign dus 



t falls compared with the 





average of the 



Madison 



analyses : 



— 







I 



II 



III 



IV 



V 



VI 



Si0 2 ... 



67.20 



53.68 



45.94 



45.40 



41.43 



36.32 



A1 2 3 .. 



13.71 



18.44 



18.35 



19.97 



10.38 



16.35 



Fe 2 3 .. 





6.54 



6.57 



7.03 



9.19 



6.08 



FeO .... 



2.17 













MgO . . . 



1.76 



1.52 



1.86 



3.13 



.92 



2.21 



CaO ... 



1.74 



.95 



8.64 



6.50 



14.10 



6.24 



Na 2 ... 



2.11 



1.67 



1.16 



2.61 



1.66 



2.59 



K o .... 



2.30 



2.58 



2.30 



2.07 



1.58 



2.72 



h;o+ .. 



3.22 













co 2 .... 







6.10 



3.46 



8.45 



3.68 



Ti0 o ... 



.52 













p 9 o; ... 



.15 







.20 







MnO .:. 



. .38 













N 



. .39 





.16 







.16 



Ignition . 



. . 5.62 



14.60 



6.73 



8.19 



5.14 



13.44 



Total . . 



101.28 



99.98 



100.00 



99.73 



99.00 



100.00 



I. Average of three analyses of dustfall at Madison, 19 

 March, 1920. 



II. Analysis after air drying of dustfall at Otakaia, New 

 Zealand, Nov. 14, 1902, which came about 1,500 miles from Aus- 

 tralia. P. Marshall : Nature, 68, p. 223, 1903. 



III. Dust in "red rain" fall at Lamberhurst, England, 22 

 Feb., 1903. 2.19% of organic carbon included in total. T. E. 

 Thorpe, Nature, 68, p. 54, 1903. 



IV. Dustfall at Naples, Italy, March 10, 1901. P. Palmeri: 

 Rend. Accad. sci. fis. Naples, (3), 7, p. 157, 1901. 



V. Dustfall at Naples, Italy, 25 February, 1879. Analysis by 

 Scacchi, quoted by P. Palmeri, loc. cit. p. 161. 4.16% of organic 

 material and 1.39% "loss" included in total. 



VI. Analysis (after air drjdng) of dustfall at Taormina, 

 Sicily, 19 March, 1901. The fall amounted to 5% tons per 



