OCTOBEE 27, 1922] 



SCIENCE 



485 



the amount of ash in coal and (3) the rate of 

 accumulation of vegetation leading to the 

 formation of coal. To the casual observer it 

 appears that there is not enough mineral 

 matter in average coal to allow for the amount 

 of atmospheric dust which would be deposited 

 with the vegetation in the time ordinarily as- 

 sumed to be required for the accumulation of 

 vegetable matter in coal. 



From everyday observation the universal 

 presence of atmospheric dust is apparent. The 

 work of Free/ Huntington,- Reid^ and others 

 emphasizes the quantit3' as being much greater 

 than commonly supposed. However, it is not 

 the amount of dust in the air, but the amount 

 that is caught in standing water or by vegeta- 

 tion that is significant in the present connec- 

 tion. 



An average of the analyses of ash content 

 for representative coals of the United States 

 given by M. R. Campbell* shows the following : 



GRADE OF COAL PERCENTAGE OF ASH 



Lignite 8.25 



Sub-bituminous 7.S 



Bituminous 8.7 



Semi-bituminous 8.7 



Semi-anthracite 11.75 



Anthracite 13.7 



The last two averages are based only upon a 

 few analyses. 



It has been stated in test-books that about 

 9,000 years is required for the accumulation of 

 sufficient vegetable matter to make one foot of 

 bituminous coal. There is no reason to believe 

 that this estimate is not at least approximately 

 correct. 



If dust was deposited from air during the 

 coal-making periods at a rate of %ooo inch per 

 year — which at the present does not seem ex- 

 cessive — 9 inches of dust would be accumulated 

 during the period of 9,000 years. Conse- 



1 Free, E. E. : " Movement of Soil Material by 

 the "Wind," U. S. Dept. of Agriculture, Bull. 68. 



2 Huntington, E. : " The Pulse of Asia. ' ' 



3 Eeid, Clement: "Dust and Soils," Qeol. Mag., 

 N. S., December, III, Vol. I, 1884, p. 165. 



4 Campbell, M. E. : " The Coal Fields of the 

 United States. ' ' General Introduction, U. S. 

 Geol. Survey, Professional Paper 100-A. 



quently, with every foot of bituminous coal 

 there should be 9 inches of atmospheric dust; 

 that is, every foot of average coal would be 

 about 75 per cent. dust. Even ^/ioooo inch of 

 dust a year would result in coal with 7% per 

 cent. dust. And this does not take into ac- 

 count the vegetable mineral matter! 



Apparently the problem leads to three ques- 

 tions: (1) Is the importance of dust grossly 

 exaggerated? (2) Has the time so commonly 

 assigned to the accumulation of a foot of coal 

 been overestimated? (3) Were the areas 

 which would serve as sources for dust during 

 the coal-forming periods — and especially the 

 Pennsylvanian — exceedingly restricted? The 

 articles cited above emphasize the presence of 

 dust in a way to induce the reader to believe 

 that the importance of atmospheric dust has 

 been overlooked rather than overestimated. If 

 the time allotted for coal formation is fairly 

 accurate, we would be led to believe that the 

 sources and perhaps the means of transporta- 

 tion of dust were very much restricted and that 

 the current evidence for a fairly moist, uniform 

 climate on a land surface heavily covered by 

 vegetation and restricted in area, becomes 

 better established. 



Waldo S. Glock 



The State Univeksitt of Iowa 



THE AMERICAN CHEMICAL 

 SOCIETY 



(Contitiued) 

 Division of Organic Chemistry 

 H. T. Clarke, chairman 

 Frank C. Whitmore, secretary 

 The selective activation of alumina for decar- 

 boxylation or dehydration: Homer Adkins. In 

 seeking experimental verification of the idea that 

 the activity of a catalyst for an organic reaction 

 in a heterogeneous system is conditioned by the 

 magnitude of the distance between the atomic 

 nuclei of the solid catalyst, five distinct kinds of 

 alumina have been prepared from the aluminum 

 alkoxides, aluminum hydroxide and hydrated 

 alumina. It has been shown that the size and 

 shape of the alkoxyl group is a determining factor 

 in the relative extent to which decarboxylation or 

 dehydration is induced in esters, alcohols and 

 acids by the alumina prepared from the solid 

 alkoxides. An increase in ' ' molecular porosity, '" ' 



