600 Winchell and Miller— 



Mr. W. J. Schnurbusch at Grand Haven, Mich., had 

 noticed the peculiar character of the snow. 



Inquiries were then sent to cooperative observers of 

 the "Weather Bureau in places remote from cities, from 

 Wisconsin, eastward to Maine. The snow unfortunately 

 had disappeared at many of these places by the time of 

 the receipt of the inquiry, and only one-third of those to 

 whom the inquiry was sent had noticed the phenomenon. 



Fig. i. 



Fig. 1. Localities where dustfalls were observed, storm of March. 7-10, 

 1918. 



These observers were J. H. Martin, Portage, Wis., F. B. 

 Hamilton, Hancock, Wis., J. Parkinson, Montello, Wis., 

 Lewis Evans, Florence, Wis., John Brown, Newberry, 

 in upper Michigan, and W. F. Dewey, Chelsea, Vt. The 

 location of these points, where dust was observed, is 

 indicated by dots on the outline map (fig. 1). 



Nature of the coloring matter. — A microscopic study of 

 the coloring matter separated from the melted snow 

 shows that it consists chiefly of inorganic substances, 

 but contains also some plant tissue. All of the material 

 is in the form of very fine particles, so that it forms a 



