A REPORT ON RESEARCHES ON THE CHEMICAL AND MINERALOGICAL COMPOSI- 

 TION OF METEORITES, WITH ESPECIAL REFERENCE TO THEIR 



MINOR CONSTITUENTS. 



By GEORGE PERKINS MERRILL, 



Head Curator of Geology , United States National Museum. 



1. INTROD0CTION AND SCOPE OF INVESTIGATION. 



In June, 1909, in view of the current speculations regarding earth history, the writer 

 published a paper on the composition of stony meteorites compared with that of terrestrial 

 igneous rocks." In the preparation of this paper he was impressed with the comparatively 

 small number of satisfactory chemical analyses available, but 99 being found which were con- 

 sidered sufficiently complete and accurate for his purpose. A second fact was the apparent 

 similarity in, and simplicity of, meteoric composition, there being shown scarcely any of those 

 elements which recent rock analyses have found to be common constituents, though in small 

 quantities, of terrestrial rocks. These facts, coupled with the occasional reported occurrences 

 of such elements as platinum, gold, lead, zinc, etc., and the high degree of perfection reached 

 by modern analytical chemistry, suggested to him the advisability of undertaking a systematic 

 investigation of the chemical nature of both stone and iron meteorites, with particular reference 

 to the occurrence of such elements as had been reported as doubtful or found only in traces. 

 On mentioning the matter to Prof. Morley, he was encouraged to make application for 

 financial assistance from the J. Lawrence Smith fimd of the National Academy of Sciences. 

 This was promptly granted, and a preliminary report of progress was published in 1913.* 

 An application for further assistance being granted, the work has been continued down to 

 approximately the present date, the analytical work, as before, being placed in the hands of 

 Dr. J. E. Whitfield, of Booth, Garrett & Blau-, in Philadelphia. 



As is well known, and was stated in the preliminary report, the nongaseous elements 

 characteristic of meteorites, the presence of which has been established by quantitative methods 

 beyond controversy, are silicon, aluminum, iron, chromium, manganese, nickel, cobalt, mag- 

 nesium, calcium, sodium, potassium, sulphur, phosphorus, and carbon. In addition there 

 have been reported, usually under such conditions as to need authentication or at least 

 corroboration, antimony, arsenic, copper, gold, lead, palladium, platinum, tin, titanium, 

 tungsten, uranium, vanadium, and zinc. The preliminary investigation above referred to was 

 made mainly for the purpose of fixing the presence or absence of these last named in amounts 

 sufficient for determination by a skillful analyst, though the possible occurrence of other 

 elemental constituents of terrestrial rocks was not ignored, and during the final researches 

 on feldspathic types great care was taken in searching for barium, strontium, and zirconium. 

 Wherever possible samples of the same meteorites in which an element had been doubtfully 

 reported were analyzed. In other cases meteorites were taken which had not before been 

 subjected to analysis, or the analyses of which were unsatisfactory for one reason or another. 

 Whenever possible, too, an amount of material was taken sufficient to warrant a representative 

 selection; as a rule 50 grams and upwards were thus utilized. In a few instances, particularly 



o Amer. Journ. Sci., vol. 2;, June, 1909, pp. 469-174. 



» On the Minor Constituents of Meteorites, Amer. Journ. Sci., vol. 35, May, 1913, pp. 509-525. 



