134 CARNEGIE INSTITUTION OF WASHINGTON. 



(8) La mesm-e des temperatures elevees par le thermometre h gaz. Ai'thur L. Day and 



R. B. Sosman. Jour. d. Physique (5), 2, 727-749; 831-844; 899-911. 1912. 



A translation into French, by Professor P. Chappuis, of "High tempera- 

 ture gas thermometry " (Carnegie Institution of Washington Publication No. 

 157, 1911). The material has been somewhat condensed and rearranged, 

 and the later work on the revision of the lower portion of the high-tempera- 

 ture scale and on the boiling-point of sulphur ("The nitrogen thermometer 

 scale from 300° to 630°, Avith a direct determination of the boiling-point of 

 sulphur," Am. Jour. Sci. (4), 33, 517-533, 1912, reviewed in Year Book 

 No. 11 (1912), p. 101) included. 



(9) Two varieties of calciovolborthite (?) from Eastern Utah. W. F. Hillebrand and H. 



E. Merwin. Am. Jour. Sci. (4), 35, 441-445. 1913. 



From chemical studies, two minerals from Paradox Valley, Colorado, are 

 considered to be varieties of calciovolborthite. In the absence of optical 

 data concerning the original mineral, the following optical properties, 

 determined from one of these varieties, are assigned to calciovolborthite. 

 Color, yellow-green, with no distinct pleochroism; biaxial, with strong 

 inchned dispersion; optically negative for blue and positive for red; a = 2.01, 

 i3Na=2.05, 7Na = 2.10. The optical properties gave evidence of monoclinic 

 symmetry. 



(10) The determination of the order of agreement between observation and theory in 



mineral analyses. Fred. Eugene Wright and C. E. Van Orstrand. J. Wash. 

 Acad. Sci., 3, 223-231. 1913. 



Of the methods available for comparing the observed results of a mineral 

 analysis with those obtained from the chemical formula to which the 

 analysis corresponds approximately, the best method is to ascertain first 

 the weight numbers (derived from the chemical formula by multiplying 

 these ratios by the proper molecular weights), and then to adjust these 

 values to the given analysis by the least-squares method. Since the compu- 

 tations involved are, however, somewhat laborious, and furthermore, since 

 there is a limited number of observations and the systematic errors of 

 observation are, in general, large as compared with the accidental errors, a 

 simpler method is preferable for general use. The method proposed fur- 

 nishes results which are very nearly correct and consists simply in reducing 

 the weight numbers proportionately so that their sum is equal to that of the 

 given analysis. In other words, we compare the actual analysis directly 

 with the weight percentage analysis computed from the inferred chemical 

 formula, both analyses having a common sum. The differences between 

 the observed and computed values are then a sufficient measure of the degree 

 of agreement of observation with theory. 



(11) A new thermal microscope for the measm'ement of the optical constants of minerals 



at liigh temperatures. Fred. Eugene Wright. J. Wash. Acad. Sci., 3, 232- 

 236. 1913. 



With this microscope three optical constants — birefringence, extinction 

 angle, optic axial angle — of a properly oriented crystal plate can be meas- 

 ured accurately at any temperature between 10° C. and 1200° C. Above 

 1200° the intensity of illumination from the furnace itself is so great that it 

 tends to veil the optical phenomena produced by the polarized light-waves 

 transmitted through the plate. The thermal microscope consists of two 

 parts: (1) a petrographic microscope equipped with a suitable device for 



