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Ref. No. : ISO/R 695-1968 (E)
IS0
I N T ER N AT I O N A L O R G A N I Z AT I ON FOR STAND AR D I ZATlO N
IS0 RECOMMENDATION
R 695
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DETERMINATION OF THE RESISTANCE OF GLASS TO ATTACK
BY A BOILING AQUEOUS SOLUTION OF MIXED ALKALI
1st EDITION
March 1968
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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.
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BRIEF HISTORY
The IS0 Recommendation R 695, Determination of the resistance of glass to attack by a
boiling aqueous solution of mixed alkali, was drawn up by Technical Committee ISO/TC 48, Labo-
ratory glassware and related apparatus, the Secretariat of which is held by the British Standards
institute (BSI).
Work on this question by the Technical Committee began in 1950 and led, in 1961, to the
adoption of a Draft IS0 Recommendation.
In December 1963, this Draft IS0 Recommendation (No. 717) 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 :
Argentina
France New Zealand
Australia
Germany Poland
Austria
Greece Spain
Belgium Hungary
Sweden
Brazil India Switzerland
Bulgaria Israel Turkey
Canada Italy U.A.R.
Chile
Japan United Kingdom
Colombia Korea, Rep. of U.S.S.R.
Czechoslovakia Ne therlands Yugoslavia
One Member Body opposed to the approval of the Draft :
U.S.A.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council,
which decided, in March 1968, to accept it as an IS0 RECOMMENDATION.
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ISO/R 695-1968 (E)
IS0 Recommendation R 695 March 1968
DETERMINATION OF THE RESISTANCE OF GLASS TO ATTACK
A BOILING AQUEOUS SOLUTION OF MIXED ALKALI
BY
1. SCOPE
The purpose of this IS0 Recommendation is to describe a method for determining the resistance of
glass to attack by a boiling aqueous solution of equal volumes ofN sodium carbonate andN sodium
hydroxide. The resistance is measured inversely by the loss in mass per unit area of the glass.
2. APPARATUS
2.1 Test vessel, of pure silver or alkali-resistant silver alloy. A recommended vessel, as shown in the
Figure overleaf, is cylindrical with a hemispherical base and has a close fitting lid The lid
has a wide neck and is fitted on the underside with four hooks from which to suspend the
samples. Where a gasket is required to ensure an adequate joint between the body and the lid, it
should be of a material which remains inert under the conditions of test.
2.2
Condenser of the Allihn or Liebig type, made of chemically resistant glass, fitted to the neck of
the vessel through a bung of suitable inert material which has previously been boiled for 60
minutes in water.
2.3 Balance accuracy +_ 0.1 mg.
2.4 Desiccator, containing a suitable drying agent.
2.5 Measuring instruments, suitable for measu
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