152 hitelligence and Miscellaneous Articles. 
Sidereal Time, Berlin. 
AR. of Comet. 
Declination of Comet. 
h m 
s 
h 
m 
s 
11 1 
14 
12 
38 
25-18 
o 
// 
11 9 
42 
12 
38 
28-26 
2 
10 
22-8 
11 21 
45 
12 
38 
32-38 
—2 
10 
13-9 
11 40 
39 
12 
38 
39-63 
—2 
9 
57-3 
These observations give its daily motion in JR, + 2° 12', in decl. 
+ 0° 19'. It has a well-defined point, as a nucleus, within the 
uniform nebula, which, opposite to the sun, expands in the form of 
a tail. 
Tables for the Calculation of Precession, for the year 1825, of 
Stars observed by M. Bessel in the several Zones, from — 15° to -f 
15° Declination. By Dr. Max. Weisse, Director of the Observatory 
at Cracow. 
Observations of Moon and Moon-culminating Stars, Eclipses of 
Jupiter’s Satellites, and Occultations of Fixed Stars by the Moon, 
made at the Observatory of Paramatta, in New South Wales, in the 
year 1838, by Mr. Dunlop. Communicated by Sir Thomas Mac- 
dougal Brisbane, Bart. 
XXIX. Intelligence and Miscellaneous Articles. 
THEORY OF SUBSTITUTIONS. ACETIC AND CHLOROACETIC 
ACIDS. 
M DUMAS has lately read the following note on these sub- 
• jects to the Royal Academy. 
In a previous memoir I have shown that chlorine decomposes 
acetic acid under solar influence, and that it gives rise to a new 
acid, which I call chloroacetic acid. On this occasion I expressed 
my opinion that acetic acid and chloroacetic acid belong to the same 
chemical type, one being represented by ; and the other by 
C® O^ CP. I endeavoured to generalize this view, and to explain 
how these types might serve to group organic bodies into well-cha- 
racterized classes. 
“ M. Berzelius, not admitting the theory of substitutions, has given, 
as soon as he became acquainted with my memoir, a refutation of 
the views announced in it. He considers acetic acid and chloro- 
acetic acid as very different from each other, because they have not 
the same density,'nor the same boiling point, nor the same odour, &c.* 
M. Berzelius has certainly not understood what I call the funda- 
mental properties of a body, for I have long known that by replacing 
the hydrogen of a compound by chlorine it is rendered more dense 
and less volatile, and at the same time the density of its vapour is 
increased. It is therefore perfectly clear to me that the objections 
made by M. Berzelius are not at all directed to the views which I 
would really express. In order therefore to avoid any fresh misun- 
derstanding, I shall endeavour to illustrate my opinion by an ex- 
ample. In causing chloroacetic acid to act upon an alkali, I ob- 
served a very remarkable reaction. The acid was converted into two 
new bodies, namely, carbonic acid, which combined with the alkali, 
* See our last Number, p. 1. 
