254: Analogy letwcen the Prismatic Spectrum [Oct. 



and carbonate of lime. This determination must be very doubtful, 

 if we consider the different proportion of carbonic acid in carbonate 

 of lime and carbonate of strontian, and recollect that Stromeyer has 

 found 3 — 4 per cent, of carbonate of strontian in arragonite. 



I might write to you bere of several other observations which I 

 made during the course of my experiments, especially of a remark- 

 able appearance which I observed during the decomposition of the 

 nitrates by a red heat ; but as I could not make you acquainted 

 with the conclusion of my experiments, I think it better to defer 

 the whole to a future letter, satisfying myself at present with having 

 confirmed and established Stromeyer's discovery. 



Article III. 



On the Analogy letween the Prismatic Spectrum and the Musical 

 Division of Sound. By David Huston, Esq. 



(To Dr. Thomson.) 

 SIR, 

 The remarkable analogy subsisting between the diatonic division 

 of sound and the prismatic division of light has been often observed, 

 and has given rise to the following observations, and perhaps sweep- 

 ing conclusions : — 



1. That the minor mode in music is the most natural ; and that 

 the prismatric spectrum exhibits that mode or key, if Newton's pri- 

 mitive colours be regarded as 1st, 3d, and 5th, or the common 

 chord. 



2. That the rays of beat accompany those of light in a spectrum * 

 of two series, in the adjoining key (to speak musically) to that of 

 light : that is to say, the " fifth" of the prismatic series (blue) is 

 adopted by the spectrum of beat for its fundamental or key-note — 

 descending and increasing in intensity till it reaches the third (being 

 there without the red ray or key-note of the visible spectrum) above 

 the diapason; from whence it diminishes in the same ratio as the 

 coloured rays, until it has completed the octave. That the rays 

 termed deoxidizing are only the more refrangible rays of heat; and 

 that they climb or extend beyond the violet ray up to the key-note 

 (or situation of blue, supposing another series of prismatic colours) 

 exclusive. 



3. That if we imagine a series of prismatic spectra in succession, 

 like the octaves of a piano-forte, we shall ever find that metals 

 oxidate doirnuards: in other words — that as their dose of oxygen 

 increases, the colours they exhibit move down in this order; tin, 

 antimony, and arsenic, being exceptions, but not violations of this 

 law. 



* I have used this word from sheer necessity. 



