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1815.) On Dalton’s Theory of Chemical Composition. 871 
Date. Wind. | Rain, Observations. 
1815. | 
June 19 S to E 0-54 { Ditto, ditto, ditto. 
20\1ik N E to WN W} Heavy showers, 
211 WNW to NW! Fair day; clondy at night, 
22 S Cloudy and fair. 
23 NW 0°09 Ditto, ditto, day; light rain at night. 
24 N to NW Misty. 
25 NW Cloudy and fair, 
26 NW Ditto, ditto. 
27 Var. Ditto, ditto. 
28 Var. * | Fair. 
29 Dp) Ditto; high wind. 
30 E Ditto, ditto. 
3°09 Inches rain. 
Wind. 
Barometer: Greatest height .......... AAR YS 30:21 inches Var. 
EO West 405). <2 on eiduatactioleveinie'a ess ESE 
DICANs- Sahtcsetie aes sate. 29°885 
Thermometer: Greatest height,....... wineries 2 76° Var, 
VOWesb.n0cene See Ne Lao ain 43 W 
BACHE Tisha afoute sg-42 TREN Sc 60°15 
ArtTicLe VI. 
Observations on Mr. Dalton’s Theory of Chemical Composition. 
By Peter Ewart, Esq. 
(Read to the Philosophical Society of Manchester, Sept. 1812.) 
Ir has long been observed that chemical compounds contain their 
elements in limited proportions ; and it has at all times been a chief 
object with chemists to ascertain these proportions in bulk, as well 
as in weight. Various attempts have been made, also, to trace some 
general principle of agreement in the phenomena of chemical com- 
In this field of investigation Mr. Dalton has been emi- 
position. 
nevtly successful, 
About ten years ago, observing a remarkable 
coincidence in the proportions of the elements contained in some 
chemical compounds, he was led to believe that this coincidence 
could not be partial or accidental, but that it might form part of a 
general system, comprehending every chemical.combination. Under 
this impression, he examined and compared, with great skill and 
ingenuity of research, a prodigious number of compounds; and he 
has published a valuable collection of facts, established by others as 
well as by himself, throughout the whole of which the principle of 
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