|
UDC n
' -->
1, *'
IS0
I N T ERN AT1 O N A L ORGAN IZ AT1 O N FOR STAND A RD IZATl O N
IS0 RECOMMENDATION
R 424
SPECIFICATION FOR PHOTOGRAPHIC GRADE
SODIUM CARBONATE, ANHYDROUS
1st EDITION
March 1965
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
---------------------- Page: 1 ----------------------
-,
---------------------- Page: 2 ----------------------
BRIEF HISTORY
The IS0 Recommendation R 424, SpeciJication for Photographic Grade Sodium
Carbonate, Anhydrous, was drawn up by Technical Committee ISO/TC 42, Photography,
the Secretariat of which is held by the American Standards Association, Inc. (ASA).
Work on this question by the Technical Committee began in 1956 and led, in 1959,
to the adoption of a Draft IS0 Recommendation.
In August 1961, this Draft IS0 Recommendation (No. 427) was circulated to all the
IS0 Member Bodies for enquiry. It was approved, subject to a few modifications of an
editorial nature, by the following Member Bodies :
Sweden
Belgium Italy
Brazil Japan Switzerland
Canada Netherlands United Kingdom
Chile New Zealand U.S.A.
Germany Romania U.S.S.R.
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0
Council, which decided, in March 1965, to accept it as an IS0 RECOMMENDATION.
-3-
---------------------- Page: 3 ----------------------
IS0 / R 424 - 1965 (E)
IS0 Recommendation R 424 March 1965
SPECIFICATION FOR PHOTOGRAPHIC GRADE
SODIUM CARBONATE, ANHYDROUS
1. SCOPE
This IS0 Recommendation is one of a series to establish criteria of purity of chemicals for
processing photographic materials. A “ photographic grade ” chemical is one which meets purity
requirements as described.
This specification states the purity requirements and test methods for photographic grade sodium
carbonate, anhydrous (Na,CO,).
2. PHYSICAL APPEARANCE
Anhydrous sodium carbonate is in the form of a granular or fine white powder.
3. SUMMARY OF REQUIREMENTS
Assay (as Na,C03) : 98.0 per cent minimum.
Bicarbonate (as NaHCO,) : 0.7 per cent maximum.
Free alkali (as NaOH) : 0.2 per cent maximum.
Halides (as NaCl) : 0.6 per cent maximum.
Heavy metals (as Pb) : 0.001 per cent maximum.
Iron (Fe) : 0.002 per cent maximum.
Reaction to ammoniacal silver nitrate : To pass test.
Appearance of solution : To pass test.
4. ASSAY (as Na,CO,)
(98.0 per cent minimum)
Dissolve 2.0 g of the sample, weighed accurately, in 50 ml of distilled water. Add 2 drops of
methyl orange indicator and titrate with 1 N hydrochloric acid *.
1 ml 1 N HCI = 0.053 g Na,CO,
* Reagents used in making the tests should be recognized reagent grade chemicals normally used for careful analytical
work. In all the directions, the acids and ammonium hydroxide referred to should be of full strength, unless dilution is
specified. Dilution is specified in terms of normality, when standardization of the reagent is required. When dilution
is indicated as (l+x), it means 1 volume of the reagent or strong solution diluted with x volumes of distilled water.
-5-
---------------------- Page: 4 ----------------------
IS0 / R 424 - 1965 (E)
5. BICARBONATE (as NaHCO,)
(0.7 per cent maximum)
Weigh 2 0.1 g of the sample into a 125 ml conical flask. Add 30 ml of freshly boiled distilled
water, stopper the flask and dissolve the sample. Add 25 ml of 1 M barium chloride (neutral to
phenolphthalein) and 10 drops of phenolphthalein indicator. Stopper and swirl. (If the solution
has a pink colour after the addition of the indicator, proceed immediately as stated in section 6.)
If the solution is colourless, titrate with 0.1 N sodium hydroxide. Not more than 1 ml of
...