538 



SCIENCE 



[N. S. Vol. XXVII. No. 692 



or dynamochemical stage. A comparative 

 study of ultimate analyses skows that in prac- 

 tically all kinds of coals, the oxygen and the 

 ash are of approximately equal anti-calorific 

 value, i. e., of nearly equal importance as im- 

 purities from the heat standpoint. Conse- 

 quently, since the carbon-oxygen ratios of 

 coals with the same ash closely correspond in 

 their numerical sequence to the order of the 

 calorific values of those coals, it follows that 

 coals with varying ash will, if arranged ac- 

 cording to the ratios of carbon divided by 

 oxygen-plus ash, C -=- (0 -f Ash) stand in a 

 sequence closely approaching that of their cal- 

 orimetrically ascertained efficiencies. Of 250 

 coals tabulated in accordance with the latter 

 ratios few depart as much as three per cent, 

 from the mean corresponding to their re- 

 spective ratios, and the greater number are 

 within one per cent. The widest departures 

 are found among the brown lignites and peats 

 and the coals undergoing anthracitization. 

 The comparative study shows that the anti- 

 calorific value of the oxygen is apparently 

 about twice as great as has been supposed. In 

 fact, per cent, for per cent., oxygen and ash as 

 impurities are of so nearly equal value ac- 

 cording to the calorimetric tests of the coals 

 as to be practically interchangeable so far as 

 concerns the heating power of the fuel. Since 

 the demonstration is based upon the analyses 

 of the air-dried samples in which the water 

 content varies widely, it would appear that 

 the oxygen of the moisture is not far different 

 in anti-calorific value from that of the oxygen 

 in hydrocarbon combination. The negative 

 value of one per cent, of oxygen, or ash, in 

 ordinary bituminous coals is probably between 

 70 and 80 calories. 



A further study of the analyses suggests 

 that the quality of coking may be due to the 

 presence of gelosic algal, or sapropelic, matter 

 in the original ingredients of the fuel. Since 

 fuels in which such matter has been micro- 

 scopically observed generally fuse, usually with 

 swelling, on combustion; and since the re- 

 searches of Renault and Bertrand have proved 

 the agency of gelatinous micro-algse in storing 

 up bitumen, it would appear probable that 



coals possessing the necessary quantity of such 

 ingredients would exhibit both fusibility and 

 enrichment by bitumen. Consequently, fuels 

 which are shown by a relatively high per cent, 

 of hydrogen to have been enriched by bitumen, 

 if such enrichment is due to the presence of 

 the above mentioned ingredients, will also pos- 

 sess the fusibility essential to coking, provided 

 that the ash is not too great. The compara- 

 tive study of the analyses shows that, until the 

 point of rapid dynamic devolatilization of the 

 semi-anthracitic stage is approached, coals 

 which exhibit a high proportion of hydrogen as 

 compared to oxygen (H/0) and which, there- 

 fore, may be regarded as enriched by bitumen, 

 generally possess coking fusibility. It thus 

 appears that the above hjrpothesis is supported 

 by chemical analyses, although it may not be 

 regarded as proven short of microscopical de- 

 tection of gelosic (sapropelic) elements. In 

 the main body of coals, between semi-bitumi- 

 nous and lignites, it would seem possible to 

 forecast the coking quality from the hydrogen- 

 oxygen ratios, moisture-free basis, of the coals. 



Philip S. Smith, 



8ecretarp 



THE PHILOSOPHICAL SOCIETY OF WASHINGTON 



The 646th meeting was held February 29, 

 President Bauer presiding. 



Mr. John E. Burbank presented the first 

 paper of the evening, entitled " Microseismic 

 Tremors and their Apparent Connection with 

 Barometric Variations." 



This paper discussed a now well-known 

 type of seismic motion which consists of short 

 period waves of very small amplitude, lasting, 

 generally, for hours and sometimes for three 

 or four days. These waves show alternate 

 maxima and minima like the phenomena of 

 beats in acoustics. 



The seismograph at the Cheltenham Mag- 

 netic Observatory recorded 75 cases between 

 September 1, 1906, and January 31, 1908. 

 The most pronounced tremors occurred when 

 a deep barometric depression passed from land 

 to sea, or vice versa. No marked depression 

 passed over the coast line, between Portland, 

 Me., and New Orleans, La., during this in- 



