As some substances, particularly in complicated compounds, are not detected with sufficient nicety in the dry way of analysis, it will often be necessary to resort to the wet way.  It is therefore necessary to have prepared the reagents required for such testing, as every person, before he can become an expert blowpipe analyst, must be acquainted with the characteristic tests as applied in the wet way.

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Part II.

INITIATORY ANALYSIS.

Qualitative analysis refers to those examinations which relate simply to the presence or the absence of certain substances, irrespective of their quantities.  But before we take cognizance of special examinations, it would facilitate the progress of the student to pass through a course of Initiatory Exercises.  These at once lead into the special analysis of all those substances susceptible of examination by the blowpipe.  The Initiatory Analysis is best studied by adopting the following arrangement: 

1.  EXAMINATIONS WITH THE GLASS BULB.

The glass of which the bulb is made should be entirely free from lead, otherwise fictitious results will ensue.  If the bulb be of flint glass, then by heating it, there is a slightly iridescent film caused upon the surface of the glass, which may easily be mistaken for arsenic.  Besides, this kind of glass is easily fusible in the oxidating flame of the blowpipe, while, in the reducing flame, its ready decomposition would preclude its use entirely.  The tube should be composed of the potash or hard Bohemian glass, should be perfectly white, and very thin, or the heat will crack it.

The tube should be perfectly clean, which can be easily attained by wrapping a clean cotton rag around a small stick, and inserting it in the tube.  Before using the tube, see also that it is perfectly dry.

The quantity of the substance put into the tube for examination should be small.  From one to three grains is quite sufficient, as a general rule, but circumstances vary the quantity.  The sides of the tube should not catch any of the substance as it is being placed at the bottom of the tube, or into the bulb.  If any of the powder, however, should adhere, it should be pushed down with a roll of clean paper, or the clean cotton rag referred to above.

In submitting the tube to the flame, it should be heated at first very gently, the heat being increased until the glass begins to soften, when the observations of what is ensuing within it may be made.