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LXII. Reply to the Observations made by Messrs. T. E. Thorpe 

 and A. W. Rucker upon our Essay entitled " Intorno ad 

 alcune for mule date dal Sig. Mendelejeff e dai Siggn. T. E. 

 Thorpe e A. W. Rucker per calcolare la temperatura critica 

 della dilatazione termica." 



To the Editors of the Philosophical Magazine and Journal. 

 Gentlemen, 



IN the course of some researches we were engaged upon 

 two years ago we found it necessary to determine the 

 critical temperature of all, or that of the greatest possible 

 number of liquids. Inasmuch as this had only been arrived 

 at experimentally in a comparatively small number of bodies, 

 it occurred to us to apply to the remainder the theories and 

 formula of Yan der Waals, and thus calculate the temperature 

 from the expansion caused by heat. We had already com- 

 menced our investigations when we became acquainted with 

 the essay by Mendelejeff on the Expansion of Liquids published 

 in the Annates de Chimie et de Physique, and with the 

 summary of it in the essay by Mr. Thorpe and Mr. Rucker 

 which appeared in the Beibldtter, entitled u On the Critical 

 Temperatures of Bodies, and their Thermal Expansions as 

 Liquids." As the formula deduced by Messrs. Thorpe and 

 Rucker from the formula of Mendelejeff involved very simple 

 calculations for determining the critical temperatures, we 

 decided to adopt it. 



Before doing so, however, we were desirous of establishing 

 to our satisfaction the relative correctness of the formula, and 

 the limits within which it could be legitimately applied. 

 This preliminary inquiry gave rise to an essay entitled 

 " Intorno ad alcune formule date dal Sig. D. Mendelejeff e dai 

 Siggn. T. E. Thorpe e A. W. Riicker per calcolare la tempe- 

 ratura critica della dilatazione termica/' published in the 

 Nuovo Cimento for July, August, and September, 1884, 

 pp. 91-104. This essay was also published in the Gazzetta 

 Chimica Italiana, vol. xiv. 1884 ; and a report of it appeared 

 shortly afterwards in the Beibldtter zu den Annalen der Physik 

 und Chemie, and also in the Journal de Physique de d' Almeida, 

 and, lastly, at the commencement of the present year, in the 

 Annates de Chimie et de Physique. Messrs. Thorpe and Rucker, 

 in a note inserted in the 'Philosophical Magazine' for May, have 

 done us the honour to reply to our essay. We feel convinced that 

 these gentlemen have only read the abridged report of our 



Phil. Mag. S. 5. Yol. 22. No. 139. Dec. 1886. 2 



