﻿On the Heating of a Disk by rapid rotation in vacuo. 97 



the fact itself disappears, and in whose hands science becomes 

 an edifice raised by their imagination." 



He declared, finally, that the Commission u had sought to ap- 

 ply to chemistry the logic which belongs to all sciences — the 

 name of class or genus recalling, in the natural order of ideas, 

 properties common to a great number of individuals, and that of 

 species properties peculiar to certain individuals." 



I do not know whether I am deceiving myself; but it seems to 

 me, moreover, that this duel of antagonist molecules which is 

 met with in all the phenomena of chemistry, and which the pre- 

 sent nomenclature expresses so well, remains incontestable, and 

 that we should not give up depicting it until we are forced to do 

 so. But the act of combination once accomplished, the duel ter- 

 minated, the French nomenclature does not pretend to say that 

 the two bodies which have acted on each other have retained their 

 distinctive character in the molecule formed and are not con- 

 founded in a complex system. It is in this respect that Berze- 

 lius, going beyond Lavoisier's idea, exaggerated the meaning. 



It is not without a legitimate satisfaction that we have the 

 right to say in this circle, that, notwithstanding the progress 

 which has metamorphosed the field of chemistry, the Academy 

 has nothing to regret, either as regards doctrine or language, of 

 what our illustrious predecessors had founded with so much 

 prudence, wisdom, and even genius. 



XIII. On the Heating of a Disk by rapid rotation in vacuo. 

 To the Editors of the Philosophical Magazine and Journal. 



Gentlemen, 

 ~V\TITH reference to the paper of Herr 0. E. Meyer, which 

 V? you translated in the last Number of the Philosophical 

 Magazine, we desire to make the following remarks. 



There was no assumption (Annahme) whatever in our statement 

 of the small but unavoidable deviation of the axis from perpendi- 

 cularity to the disk. The amount of this bias was, in each case, 

 directly measured by turning the disk so slowly that no flexure 

 could possibly be produced by the rotation • and the amount thus 

 determined was not visibly exceeded even at the highest speeds. 

 The length of the axis is nearly, 4*5 inches (or more than two- 

 thirds of the radius of the disk) ; and it lies in two bearings which 

 fit it as tightly as is consistent with free rotation. The utmost 

 amount of deflection of the edge of the disk due to slackness of 

 these bearings cannot possibly be nearly as great as 0*001 inch. 



Herr O. E. Meyer supposes, contrary to the usual principles 

 of ordinary dynamics, that a change of position of the instanta- 



Phil Mag. S. 4. Vol. 37. No. 247. Feb. 1869. H 



