Di\ A. M. Mayer's Researches in Acoustics. 259 



2. There is great difficulty in accounting for the reduction 

 of the metal by purely chemical processes. 



3. Arrhenius's hypothesis of ionic dissociation in names is 

 a chemically acceptable way of accounting for the liberation 

 of sodium when its salts are heated in flames. 



4. There is no direct evidence and no decisive indirect 

 evidence that the sodium spectrum is the direct consequence 

 of the chemical action in which the atoms are engaged. 



Postscript. 



In a recent number of Wiedemann's Annalen * there is a 

 paper by Paschen in which he shows by bolometric mea- 

 surements that the invisible spectra of hot gases exhibit 

 distinct maxima of intensity — that, in short, gases do give 

 discontinuous spectra on being heated, independently of 

 chemical action. On these grounds and others, some of 

 which are similar to those explained in the foregoing paper, 

 Paschen does not consider that Pringsheim's conclusions can 

 be accepted. 



[To be continued.] 



XXIII. Researches in Acoustics. — No. IX. By Alfred M. 



Mayer, Ph.D.\ 



Contents. 



1. The Law connecting the Pitch of a Sound with the Duration of its 



Residual Sensation. 



2. The Smallest Consonant Intervals among Simple Tones. 



3. The Durations of the Residual Sonorous Sensations as deduced from 



the Smallest Consonant Intervals among Simple Tones. 



1 . On the Law connecting the Pitch of a Sound ivith the 

 Duration of its Residual Sensation. 



IN October 1874 I published in the American Journal 

 of Science Paper No. 6 of Researches in Acoustics, 

 which contained an account of my attempts to establish the 

 law connecting the pitch of a sound with the duration of its 

 residual sensation. The law given in that paper was the 

 expression of the results of the first experiments, extend- 

 ing through several octaves, ever made on the duration of 

 sonorous sensations. 



Subsequently, in April 1875, I published in the American 

 Journal of Science { the results of similar experiments which 



* Vol. 50. p. 409 (1893). 

 t Communicated by the Autho r. 



% The papers cited above were published in the Philosophical Magazine 

 of May 1875, in one paper, " Researches in Acoustics, No. VI." 



