GEOPHYSICAL LABORATORY. 99 



and could, therefore, be largely eliminated, but might prove decidedly decep- 

 tive if overlooked, and if the heat effect was, as often happens, one occurring 

 only in the first heating. This circumstance well illustrates the care which 

 must be taken to avoid systematic errors in this kind of work, and the danger 

 of assuming too hastily that the precautions in this direction have been 

 sufficient. 



(i8) Die Schmelzpunkte der Mineralien im Lichte nearer Untersnchungen iiber das 

 Gasthermometer. Arthur L. Day und Robert B. Sosman. Z. anorg. Chem. 72, 

 I. 1911. 



A German translation of "The melting-points of minerals in the light of 

 recent investigations on the gas thermometer" (Am. J. Sci. (4), 31, 341, 

 1911). Reviewed under No. lo (p. 94). 



(19) Der Einfluss des Druckes auf die Schmelzpunkte einiger INIetalle. John Johnston 



und L. H. Adams. Z. anorg. Chem. "jz, 11. ipri. 



.\ German translation of "The influence of pressure on the melting-points 

 of certain metals" (Am. J. Sci. (4), 31, 501, 191 1). Reviewed under Xo. 12 

 (P-95)- 



(20) High-temperature gas thermometry. Arthur L. Day and Robert B. Sosman. With 



an investigation of the metals by E. T. Allen. Publication No. 157, Carnegie 

 Institution of Washington. 



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

 up the task of redetermining the absolute temperature scale from 400° to 

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

 practicable to do so, to 1600° C, covering the region in which 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 investi- 

 gation. One, a brief summary of preliminary work up to 1100°, was given 

 before the National x\cademy of Sciences and the American Physical Society 

 in April 1907 ;* the second covered the same ground at considerable length 

 in 1908. t A final paper J extending the observations to 1550° and a supple- 

 mentary paper § on the use of thermo-elements throughout the entire range 

 from zero to melting platinum appeared in 1910 and completed the work 

 contemplated under the original plan. 



The gas-thermometer problem at the present stage of its development has 

 become primarily a problem for experimental study with two definite pur- 

 poses, one to increase the accuracy of the measurements, the other to increase 

 their range. The application of the gas laws is no longer subject to serious 

 question. The progress of recent years has given us electric heating in place 

 of gas and the consequent possibility of controlling the temperature with 

 great certainty and exactness. It has also given us the metal bulb with a 

 definite and measurable expansion coefficient and capable of holding the 

 expanding gas w^ithout loss. It has discovered a gas which does not dift'use 

 through the bulb or react with it chemically, which does not dissociate within 

 the limits of practicable measurement, and of which the expansion can be 

 expressed with reasonable certainty in terms of the Kelvin thermodynamic 

 scale whenever it may prove necessary or desirable to do so. It has also 

 discovered the source of the errors in the thermo-elements and a way to 

 avoid them. 



* Abstract. Phys. Rev. 24. 531. 1907. 

 t Amer. Jour. Sci. (4) , 26, 405-463. 1908. 

 4 Amer. Jour. Sci. (4), 29, 93-161. 1910. 

 § Amer. Jour. Sci. (4), 30, 1-15. 1910. 



