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37
den kulsure Kalk i Leret har jeg benyttet et af S. W.
Johnson konstrueret Apparat (Zeitschrift für anal. Chemie,
9, S. 90). Dette er fortrinlig skikket til en hurtig og
sikker Bestemmelse af Kulsyren i de let dekomponerbare
Karbonater. Johnsons Apparat har den Fordel fremfor
of carbonate of lime present in oceanic deposit, I made
use of an instrument devised by S. W. Johnson (Zeitschrift
für anal. Ghemie, 9, S. 90). and admirably adapted for
speedy and accurate determination of the carbonic acid in
easily decomposable carbonates. Johnson’s apparatus has
Bunsens og de øvrige, at det »ikke nødvendiggjør nogen
Udsugning og Udkogning for at fjerne den tilbageblevne
Kulsyre. Apparatet (se ovenstaaende Tegning) med den
afveiede Substans fyldes (gjennem a) med tør Kulsyre fra
et Udviklingsapparat og veies; derpaa holdes det paaskraa,
saa at Saltsyren fra det pæreformige Reservoir rinder over
i Kolben. Naar Karbonatet er fuldstændig dekomponeret,
ledes Kulsyre atter igjennem og Yeiningen udføres paany.
Bestemmelsen kræver neppe en halv Time.
Med Apparatet fandt jeg i kulsur Baryt ved to
Bestemmelser: 22.27 pCt. og 22.20 pCt.: beregnet: 22.33 pCt.
I Bundpr. fra St. 300 fandtes ligesaa 2.46 pCt. og 2.55 pCt. C02
I _ „ „ 53 — — 12.70 — 12.81 —
Altsaa en Nøiagtighed som ikke lader noget tilbage at
ønske.
this advantage over Bunsen’s and other instruments of the
kind, that no absorptive, boiling-out process is necessary
to get rid of the residuary carbonic acid. The apparatus in
question (see Fig. ), containing a given quantity of the
substance, is filled (through a) with dry carbonic acid, and
duly weighed; it is then held obliquely, that the
hydrochloric acid from the pyriform reservoir may flow into the
flask." So soon as the carbonate of lime is completely
decomposed, the carbonic acid is again conducted through
the apparatus, and the weighing carried out as before.
Half an horn- will amply suffice for the operation.
With this apparatus, I found in carbonate of baryta,
as the result of two determinations, respectively 22.27 per
cent and 22.20 per cent of carbonic acid (by computation
22.33 per cent). Again, in the sample of the bottom brought
up at Station 300, the proportion thus determined was
2.46 per cent and 2.55 per cent; in that from Station 53,
12.70 per cent and 12.81 per cent, — a degree of
accuracy that leaves nothing to be desired.
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