On a Systematic Arrangement of Colours. 1l¢ 
-It is added that this discovery is of great moment, as it 
removes an anomaly, which hitherto remained, against the 
general law in the congelation of liquids, (alluding no doubt 
to the congelation of alcohol,) viz. that all liquids become 
solid at a certain temperature. 
That alcohol itself, at present the measure of low tem- 
peratures, would become solid as well as other liquids, pro- 
vided a sufficient degree of cold were produced, no person, 
I should think, ever doubted. 
It is a well known fact, respecting the congelation of the 
mineral acids, that the most concentrated state of them 15 
by no means that in which they resist the greatest cold 
without freezing. It is possible this may be the case with 
respect to alcohol, but this does not appear very probable. 
If it be an ascertained fact, that a temperature sufficiently 
cold can be produced by art to fix or freeze alcohol, or 
spirit of wine, of any strength, we must in future look for 
some other measure of low temperatures than liquids ; and 
of course, in such a case, a thermometer of metallic con- 
struction would naturally present itself *, 
I have merely made these cursory remarks, being en- 
gaged at this time in other pursuits, for the reason assigned 
above ; and when the fact is clearly and accurately esta- 
blished, I shail adopt it in the stead of the one I at present 
consider myself bound to adhere to, 
Oxiord, July 6, 1813. Rp. WALKER. 
Sa nea ee ee oT 
XX. On a Systematic Arrangement of Colours. By 
Tuomas Forster, Esq. 
To Mr. Tulloch. 
Sir, Aone the desiderata of philosophy may be included 
the want of a systematic arrangement of colourst, with 
specific names for each, whereby the numerous combina- 
tions and shades of colour, which appear on the surtaces of 
bodies, may be expressed with greater precision than they 
can be at present with our imperfect and indefinite names. 
I was first induced to think on this subject irom the great 
difficulty that [ experienced from time to time in conveying 
on paper an adequate idea of the various and dissimilar unts 
* J allude to the contraction or elongation of metallic wire according to 
changes of temperature. See a paper on this subject, Phil, May. Aug. 1810, 
page 119. 
+ In future, perhaps, some theory of smells may be formed by repeated 
experiments with compounds of them. Something like what Haller ts said 
to have had in view. : 
H4 displayed 
