Full resolution (JPEG) - On this page / på denna sida - Sidor ...
<< prev. page << föreg. sida << >> nästa sida >> next page >>
Below is the raw OCR text
from the above scanned image.
Do you see an error? Proofread the page now!
Här nedan syns maskintolkade texten från faksimilbilden ovan.
Ser du något fel? Korrekturläs sidan nu!
This page has never been proofread. / Denna sida har aldrig korrekturlästs.
brændte Surstofgasen med overskydende Vändstof. Han
brugte ogsaa her som Spærrevædske Vand. som paa
Forhaand var mættet med Luft, og det kan saaledes ikke
forundre. at de Resultater, han erholdt, vise temmelig
betydelige Afvigelser. Surstofmængden varierer saaledes fra 39.5
til’ 31.0 og udgjør i Middel 34.7 !’/„ af den samlede
Surstof-Kvælstofmæugde, medens denne varierer mellem 20.0 og
30.5 og i Middel udgjør 24.5 CC. pr. Litre af det udkogte
Vancl. Som inan heraf ser, svarer den midlere
Surstofpro-cent meget nøie med det af Bunsen senere for destilleret
Vand opstillede Tal. hvorimod de Tal, Morren opfører som
Udtryk for den samlede Surstof-Kvælstofmængde, ingen
nøiagtig* fixeret Betydning have, da han intetsteds angiver
den Barometerstand og Temperatur, hvortil han har
reduceret sine Gasvolumina.
Nogle Aar senere i’ 1846 gjenoptog Lawy1 Morrens
Undersøgelser paa nogle Vandprøver, som han øste ved
Langrune i Nordost for Saint-Malo. og anvendte for at
kunne sammenligne sine Resultater med Morrens nøiagtig
den af ham beskrevne Arbeidsmethode. Hans Resultater
vise ogsaa, naar man tager Hensyn til. at Vandprøverne
alle skrive sig fra samme Sted, ikke ubetydelige om end
meget mindre Afvigelser, som han ligesom Morren
tilskriver Sollysets Indflydelse. Surstofmængden varier hos ham
fra 35.4 til 32.4 og udgjør i Middel 33.0 °/0 af den samlede
Surstof-Kvælstofmængde’, som gjennemsnitlig beløber sig til
17.3 CC. pr. Litre • og ikke overskridç’r Grændserne 18.9
og 10.3. Heller ikke Lewy har nærmere fixeret
Betydningen af de opførte Gasvolumina. Der har forresten i hans
Tabel indsneget sig meningsforvirrende Regnefeil, som har
givet Anledning til. at haft er bleven misforstaaet.
I 1851 har endvidere A. Haves- offentliggjort nogle
Udtalelser" om Fordelingen af Luften i Søvandet dog uden
at vedføie sine Originalobservationer. Ifølge ham tindes i
Vand fra større Dyb altid en betragtelig mindre Mængde
Surstof end i Overfladevandet, en Regel, som overalt holdt
stik saavel i den hede som tempererede Zone. naar
undtages i Golfstrømmen, hvor den stærke Bevægelse i Van-,
det kunde antages at forstyrre den almindelige Ligevægt.
Han fandt ogsaa efter Storme en betydelig større
Surstofmængde i Overfladevandet.
I 1855 udførte M. F. Pisani3 nogle Undersøgelser af
Saltene i Overfladevandet ved Bujuk-Déré og bestemte
samtidig de i Vandet indeholdte Gasarter. Resultaterne findes
sammenstillede i nedenstaaende Tabel, hvor Volumet er
reduceret til .0° og 7(30mm Tryk og udtrykt som CC. pr.
Litre Vand.
’ Ann. Clfim. Phys. [3] — 17. Ann. Chem. Pharm. .">8 — 326.
2 Sil lim. Arner. Journ. [2]—11—241.
3 Compt. rend. 41 — 532.
potash for absorbing the carbonic acid, and consumed
the oxygen with a surplus of hydrogen. Here, too, the
confining fluid was water, previously saturated with air:
and hence it is not surprising, that the results obtained
should have been’ found to vary considerably. Thus, for
instance, the amount of oxygen varies between 39.5 and
and 31.0 per cent, the mean proportion being 34.7 of the total
amount of oxygen and nitrogen; while the latter ranges
from 20.0 to 30.5. giving a mean proportion of 24.5 M
per litre. The mean percentage of oxygen agrees, therefore,
very closely with the proportion afterwards found by
Bun-sen for distilled water: whereas- no definite importance
can be attached to Morrens figures representing the total
amount of oxygen and nitrogen, since that observer does
not anywhere state to what temperature and atmospheric
pressure he had reduced the ’volume of the gas.
Some years after, in 1840, Lewy1 repeated Morren’s
experiments, with samples of water drawn at Langrune,
north-east of Sairit-Malo. adopting, the better to compare
his results with those of Morren, precisely the same mode
of operation. The results obtained by this chemist,
seeing that the samples of water were all of them frOm
the same locality, vary, too, considerably, though by no
means to the same extent. — which he. in common with
Morren, ascribes to the influence of solar light. The amount
of oxygen ranges from 35.4 to 32.4—33.0 per cent, being
the mean proportion of the total amount of oxygen and
nitrogen, which averages 17.3^. per litre, having in no
case passed the limits 18.9 and 10.3. Lewy. too. omits
to give, the factors determining the volume of the gas.
.Moreover, divers perplexing errors have slipped into his
Table; and hence he has been misunderstood by some.
In 1851. A. Hayes2 published a paper on the
distribution of air in sea-water, without however embodying his
original observations. According to the observations of
that chemist, the amount of oxygen in water drawn from
great depths is always appreciably less- than that in
surface-water. a rule which holds good for all seas both of the
torrid and the temperate zones, with the exception of the
Gulf Stream, where the strong current may be supposed
to exert a disturbing influence. After a lieavy gale of
wind, too, the proportion of oxygen in the surface-water
was found to be much greater.
Li 1855, M. F. Pisani3 instituted a series of
observations near Bujuk-Déré on the salts in surface-water, and
also determined the gaseous bodies it contained. His
results are given in the following Table, the volume
.being reduced to a temperature of 0° and a pressure of
7G0mm. expressed in cubic centimetres per litre.
1 Ann. Chim. Phys. :’.], IT: Ann. Chem". Pharm. .">8, p. 326.
2 Sillim. Amer. Journ. [2], 11, p. 241.
3 Compt. rend. 41. p. 532.
<< prev. page << föreg. sida << >> nästa sida >> next page >>
