~ 
: 
378 Magnetical Observations. [Noy 
in opposition to the explanation which Berthollet has attempted to 
give of chemical affinity. But if Berthollet’s opinions with regard 
to the effect of quantity on what he understands to be the relative’ 
forces of chemical affinity were established, not only Mr. Dalton’s 
observations, but almost all the conclusions of chemists, respecting 
composition, would be overturned. ‘The errors of Berthollet, how- 
ever, have been distinctly pointed out by Proust (Jour. de Phys, lis. 
1804); and it is surprising that so good a chemist, and so accurate 
a reasoner, as Berthollet, should have mistaken so many mechanical 
mixtures for chemical compounds. 
The agreements observed by Gay-Lussac in the relative bulks of 
gases which enter into combination with each other are in some in- 
stances in conformity with Mr. Dalton’s observations respecting 
their relative weights. In other instances, when he states certain’ 
_yelations to exist between the bulk of the compound and its ele- 
ments, he is at variance with Mr. Dalton; and the question between 
them can be determined only by repeated experiments. 
It is obvious, however, that whatever agreements may be traced 
in the relative bulks of the elementary gases, all such proportions 
must he lost when the gases are changed into fluids or solids. 
Mr. Dalton’s explanation has the advantage of not being affected 
by the specific gravities of the elements or of the compound; and 
it applies equally to gases, fluids, and solids. 
' 
ArticLe VII. : 
Magnetical Observations at Hackney Wick. By Col. Beaufoy. 
Latitude, 51° 32 40°3'’ North, Longitude West in Time 6”-3,35. 
1815, 
Morning Observ. Noon Observ. Evening Observ. 
Hs oy) 3 CR Sak oh Lae ee as 0 bs SE A Pd 
Hour. | Variation. | Hour. } Variation. } Hour. | Variation. 
Sept. 18] 8h 20/1249 15’ 41/7 Ih 55/|24° 18/ 51”) Gh 15! 124° 17! 17” 
Ditte 1918 15)— 15 48 /— ~—~J— ~— —f[— —i—- — — 
Ditto 20) 8 25 |24 14 43]1 30 |24 21 43/16 05 |24 17 33 
Ditto 21} 8 30 j24 18 32}1 35 |24 23 O1)} 6 15 \24 16 30 
Ditto 22} 8 20 |j24 14 17 {1 50 |24 21 30}]6 OO 24 19 10 
Ditto 23} 8 40 |24 15 06] 1 40 24 21 0316 05 24 16 43 
Ditto 24,8 25 j24 14 15|/- —|— — —|6 05 24 18 26 
Ditto 25} 8 25 24 13 25)|1 40 |24 23 28) 6 05 24 18 O02 
Ditto 26, 8 20 124 15 00} } 35 124 29 46/6 00/24 15 33 
Ditto 27} 8 20 124 16 00} 1 20 \24 18 00] 6 00 \24 20 24 
Ditto 28} 8 00 24 23 20} 1 15 |24 24 31}5 50 \24 24 O08 
Ditto 29} 8 25 |24 22 36}1 20 124 25 31}5 50 (24 23 It 
Ditto 30!'8 35 \24 20 06'1 25 24 26 5415 55 24 QI 22 
Ce a 
