GEOPHYSICAL, IvABORATORY. 



93 



AbgAiiioCgi. The molecule NagO AUOg 2 SiOg is anorthite in which cal- 

 cium has been replaced by soda. Crystals of this soda anorthite were first 

 made by S. J. Thugutt, who found that they also resembled anorthite in the 

 thin section. Crystals of this substance have also been made in the Geo- 

 physical Laboratory and studied microscopically and the conclusions of 

 Thugutt corroborated. No evidence was obtained opposing the hypothesis 

 of crystal solution. For the Linosa feldspar itself, the name Anemousite is 

 proposed, while for the term soda-anorthite, which is open to serious objec- 

 tion, it is suggested that the name Carnegieite be substituted, in honor of the 

 Institution under whose auspices the present investigation was undertaken. 



(3) The nitrogen thermometer from zinc to palladium. Arthur L. Day and Robert B. 

 Sosman. With an investigation of the metals, by Eugene T. Allen. Am. 

 Journ. Sci. (4),29, 93. 1910. 



It is now something over five years since the Geophysical Laboratory took 

 up the task of redetermining the absolute temperature scale from 300° to 

 1100° with the nitrogen thermometer, and of extending it, if it should prove 

 practicable to do so, to 1600° C, for in this upper region are found most of 

 the mineral relations which it is the chief purpose of the laboratory to study. 

 Two preliminary publications have been made during the investigation 

 (Phys. Rev., 1907; Am. Journ. Sci., 1908). The present paper extends the 

 earlier observations to 1550°, and completes the work contemplated under 

 the original plan. 



No attempt will be made to oflfer an inclusive summary of the whole in- 

 vestigation. It is a record of experimental measurements covering an un- 

 usually wide range of details which do not admit of brief classification. 

 The errors which have heretofore been present in measurements with the 

 nitrogen thermometer have been reduced by the present investigation to 

 about one-fourth their former magnitude, and the certainty of their evalua- 

 tion is at least proportionally increased. Careful analyses were made of all 

 the metals used as standards. 



The chief source of present uncertainty is the temperature distribution 

 over the surface of the bulb in an air-bath. No indication of a limit to the 

 temperature attainable with the nitrogen thermometer or to its ultimate accu- 

 racy was discovered during the present investigation. 



The melting temperatures of the metals and salts which have been used as 

 fixed points to establish the new scale are brought together in the table 

 below. To this table has been added a new estimate of the melting tempera- 

 ture of platinum, obtained by adding the optically determined difference be- 

 tween the melting points of palladium and platinum to our determination of 

 the palladium point. 



Diopside (pure) i39i-2 ± i-5 



Nickel 14S2.3 + 2.0 



Cobalt 14S9.8 r!- 2.0 



Palladium 1549-2 ± 2.0 



Anorthite (pure) 1549-5 ± 2.0 



Platinum 1755-° 



Cadmium 320.0 ± 0.3 



Zinc 418.2 ± 0.3 



Antimony 629.2 ± 0.5 



Alumiuium 65S.0 ± 0.6 



Silver 960 o ± 0.7 



Gold 1062.4 ± 0.8 



Copper 1082.6 ± 0.8 



(4) High-temperature gas-thermometry and its present limitations. Arthur L. Day. 

 Metall. and Chem. Eng., vni, 257. 1910. 



A brief review of recent progress toward the establishment of trustworthy 

 reference temperatures in the region between 1000° and 1600° C, for the 

 information of engineers. 



