Preliminary tests on the semimicro scale

4 PRELIMINARY TESTS ON THE SEMIMICRO SCALE In most cases samples submitted for analysis are solid. The preliminary tests 1-8 described in this section are to be carried out on solid samples. If the sample is liquid (e.g. a solution), these tests can be omitted, though tests 3-8, with little modifications, might be useful even for such samples. Preliminary tests to be carried out with liquid samples are described under test 9. 

Testing for appearance [Section V.2, test 1] will not be described again it is useful however to carry out such an examination, using a magnifying glass or a microscope, as described there. 

Vapour is evolved test with litmus paper. 

Dinitrogen oxide (rekindles a glowing splint) and steam are evolved. 

Dark-brown or reddish fumes (oxides of nitrogen) acidic in reaction. 

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