768 Scientific Intelligence. 



furnace at atmospheric pressure, and at temperatures up to about 

 2400° C, are due to the action of heat on a chemical compound 

 of the metal and not on the uncombined metal alone. Therefore 

 these spectra are not of purely thermal origin. 



(6). A spectrum of iron has been observed at the low tem- 

 perature of 1500° C. and found to be the same as that emitted 

 by an air name burning in coal gas. 



(c). The spectra of iron compounds in flames are identical 

 with the furnace spectra at corresponding temperatures up to 

 about 2400° C. All the lines of evidence lead to the conclusion 

 that the mode of excitation must be the same in the two cases, 

 namely, chemical dissociation of an iron compound by thermal 

 action. 



(d). The character of the spectrum is independent of the 

 nature of the iron compound ; thus chlorides, oxides, etc., always 

 give the same kind of spectrum in either the flame or furnace at 

 a given temperature. 



(e). The name thermo-chemical excitation has been suggested 

 to designate the cause of emission of the spectra in question. 

 These spectra differ completely from the spectra radiated by the 

 same compounds in the explosion region of the air coal-gas flame 

 in which the emission is due to chemical excitation at a com- 

 paratively low temperature. 



(/). The aluminium lines at A.3944 and A3962 have been 

 observed at the low temperature 1500° C. — Phil. Mag., 36, 209, 

 1918. h. s. u. 



8. Publications of the American Astronomical Society; Vol- 

 ume 3. Pp. 372. 1918 (Published by the Society).— This 

 volume contains the reports of the meetings of the society, begin- 

 ning with the sixteenth (1913) and ending with the twenty -first 

 (1917). In the majority of cases the scientific papers presented 

 at the several meetings are given in abstract form. The chief 

 exceptions to this general statement are afforded by the address 

 (March, 1914) by Henry Norris Russell, on the "Relations 

 between the Spectra and other Characteristics of the Stars, ' ' and 

 by the reports of the committee on stellar parallaxes. Pages 347 

 to 372 contain the constitution and by-laws, lists of the officers 

 and members, author and subject indexes, etc. The unavoidable 

 uniformity of the text is greatly relieved by eight full-page, half- 

 tone reproductions of excellent photographs of the members 

 present at the meetings, of Percival Lowell, and of certain new 

 astronomical observatories. h. s. it. 



II. Geology. 



1. Maryland Geological Survey; Edward B. Mathews, State 

 Geologist. Vol. X. Pp. 553, 96 text figs., 1918; and Anne 

 Arundel County. Pp. 232, 9 pis., 4 text figs., atlas of 4 maps, 



