106 Prof. W. K Hartley and Mr. H. Kamage. The Mineral 



with such an origin. The only meteorite which contains as much lead 

 as this is the siderolite from Atacama. 



Of Volcanic Bust. 



If we examine the spectra of specimens of volcanic dust it is notice- 

 able that the heavy metals are, without exception, in comparatively 

 small proportions — lead and iron, for example — while lime, magnesia, 

 and the alkalies are the chief basic constituents. The spectra of the 

 heavy metals, the alkaline earths, and the magnesia with the alkalies 

 appear on separate photographs. 



Of Soot from different Chimneys. 



The nature of soot from different sources is characterised by the 

 small proportion of iron in most specimens and of metals precipitated 

 as hydroxides ; its large proportion of lime and the greater variability 

 in the proportions of its different constituents distinguishes it from 

 other kinds of dust collected from the clouds or in the open air. It 

 was certainly unexpected when nickel, calcium, manganese, copper, and 

 silver were found to be constant constituents of soot from different 

 chimneys and flues. The proportions of lead, silver, and copper are 

 much larger in the soot from the assaying furnace and the laundry 

 chimney. 



To illustrate the differences observable in dust and soot of various 

 kinds, a list is appended of the wave-lengths of the iron lines observed 

 in the spectra from soot obtained from the laundry, laboratory, kitchen, 

 and bedroom chimneys. A second list gives the wave-lengths of lines 

 belonging to other elements and observed in other substances as well as 

 dust and soot. 



It wall be seen thac- nere is an extraordinary difference between 

 the kitchen and the laundry soot, which is probably caused by a higher 

 temperature and more complete combustion of the fuel in the laundry 

 fire. 



Flue Dust. 



In flue dust from different sources the chief characteristics are the 

 presence of lead, silver, and copper in larger proportions than in other 

 varieties of dust or of coal ashes which have also been examined. 

 Nickel and manganese also are in larger proportions. But the most 

 striking feature is the quantity of rubidium, gallium, indium, and 

 thallium in all samples examined. 



It is evident now that we can state with absolute certainty whether 

 two kinds of dust have the same composition or in what constituents 

 they differ substantially. 



When dust is collected in the open air it is liable to become mixed 



