44 Chemistry and Physics 



No. 157. DAY, ARTHUR L., and ROBERT B. SOSMAN. High Temperature Gas Ther- 

 mometry. With an Investigation of the Metals, by E. T. Allen. Oc- 

 tavo, vi+129 pages, 1 plate, 18 figures. Published 1911. Price $1.25. 



An account of a new determination, with the nitrogen thermometer, of the funda- 

 mental scale of temperatures, beginning with 400 C. and extending to 1550* C. Its 

 purpose was partly to increase the accuracy of the existing (Reichsanstalt) scale, 

 which reaches only to 1100, but more particularly to -extend the scale beyond this 

 temperature as far as it should prove practicable to go without serious sacrifice of 

 accuracy. It proved possible to establish the melting-point of pure palladium 

 (1549.5) with a probable uncertainty of no more than 2. 



Two bulbs were used, one of platinum containing 10 per cent of iridium, the other 

 of platinum containing 20 per cent of rhodium. The latter material proved to be 

 better suited to the purpose than any which has hitherto been tried. In the experi- 

 mental development of the problem, the errors of the older (Reichsanstalt) instru- 

 ment, so far as known were reduced to about one-fourth of their former magnitude. 



No. 158. WRIGHT, FRED. EUGENE. The Methods of Petrographic-Microscopic 

 Research: Their Relative Accuracy and Range of Application. Octavo, 

 204 pages, 11 plates, 118 figs. Published 1911. (Out of print.) Price $2.50. 

 In this paper the petrographic microscope is treated as a measuring device for the 

 exact determination of the optical properties of crystal plates, especially of minute 

 crystal fragments and crystallites. The methods now available for the purpose are 

 considered with special reference to their accuracy and applicability to the investiga- 

 tion of fine-grained silicate preparations. The factors underlying the determination 

 of any given optical property are discussed in detail, and the attempt is made in each 

 case to ascertain the absolute accuracy attainable. 



No. 40. BARUS, CARL. Nucleation of the Uncontaminated Atmosphere. Octavo, 



xii+152 pages, 104 text figures. Published 1906. Price $1.00. 

 This book contains as its chief feature a record of the dust content of the air at 

 Block Island, Rhode Island, in comparison with identical observations made at the 

 same time in Providence, Rhode Island, throughout the winter of 1904-1905. In 

 winter the former locality is relatively uninhabited and is surrounded by water on all 

 sides. It is shown that the time distribution of nuclei in both places is qualitatively 

 the same, although in Providence it is four to ten times larger quantitatively. In 

 the introductory chapters a number of independent correlative experiments are in- 

 cluded, referring to condensation on ions and on the vapor nuclei (colloidal nuclei) 

 of dust-free wet air, to the production and distribution of persistent nuclei pro- 

 ducible by the X-rays, to the penetration of radium radiation through different 

 media and different distances, etc., all interpreted by measuring the apertures of the 

 coronas of cloudy condensation. 



No. 62. BARUS, CARL. Condensation of Vapor as induced by Nuclei and by Ions. 



Octavo, x-j-164 pages, 66 text figures. Published 1907. Price $1.50. 

 The purpose of this book is the development of a capacious fog-chamber, effi- 

 cient enough to capture the ions and the vapor nuclei of dust-free wet air by con- 

 densation, to the extent in which their number per cubic centimeter may be measur- 

 able by aid of the coronas of cloud particles. As the apertures of the coronas 

 eventually become very large, approaching 60, and a reasonable exhibit of coronal 

 colors is essential for identification, the need of a large apparatus is apparent. Equa- 

 tions are deduced for the practical treatment of the variables involved. Experiments 

 made with water and alcoholic vapors in different gases establish the nature of the 

 vapor nuclei of dust-free media. In continuation of the atmospheric work of the 

 preceding report, a comparison is made of the ionization and the dust contents of 

 the atmosphere in a series of observations extending over several months. 



No. 96. BARUS, CARL. Condensation of Vapor as induced by Nuclei and Ions. 



Report III. Octavo, vi+139 pages, 48 figs. Published 1908. Price $1.25. 



After summarizing the thermodynamic equations which determine the efficiency 



of the plug-cock fog-chamber, the author continues his work on the changes of the 



