Professor Qrenville A. J. Cole — On Flame- Reaction. 105 



(i) From a crushed and pure sample of the silicate or groundmass, 

 select a bulk of about two cubic millimetres. This is about twice 

 the bulk used in the ordinary Szabo reactions. 



(ii) Place the cone on the star-support round the lower part of 

 the Bunsen-buruer, the flame rising some 15 cm. above it. 



(iii) On the end of the platinum wire make a loop aboiit 2 mm. 

 in outer diameter; dip it into water — all ordinary waters are 

 sufficiently free from potassium — and pick up on it powdered sodium 

 carbonate. Fuse this into a bead covering the loop. 



(iv) Examine the flame produced by this bead through 5 mm. of 

 blue glass, and note that the blue column in the flame has no violet 

 fringe. 



(v) Eemove the bead from the flame, dip it into water, and pick 

 up the selected particle or particles of the assay. 



(vi) Fix the wire on the support, so that its loop falls in Szabo's 

 position, in the edge of and enveloped by the flame, and 5 mm. 

 above the top of the cone. Leave it for two minutes, noted by the 

 watch. 



(vii) Then examine the resulting flame edgewise, i.e. with the 

 plane of the blue glass upright and parallel to the length of the wire. 

 If potassium is present, a violet flame will be seen, on the inner side 

 of the blue column produced by the intense sodium. The intensity of 

 colouration is as important quantitatively as the extent of the flame. 

 This flame is persistent for ten minutes or more, and may thus be 

 examined at leisure. 



(viii) In some few cases, a further intensification may be required. 

 Eetnove the bead, dip it into a drop of strong hydrochloric acid, and 

 insert again in the flame. The flames from the chlorides thus 

 formed rival those produced by the sulphates under the best con- 

 ditions of the experiment with gypsum. 



I find it sufficient to tabulate the results obtained by the method 

 described in paragraph vii under three grades : — 



Grade 1 = about 4 per cent, of potash. 



J? o = ,, lA ,, ,, 



I would advise each worker, however, to establish these grades 

 for his own eye and his own blue glass, upon specimens of known 

 and analyzed minerals. 



Where only the qualitative result is required, the flame may be 

 viewed from the back, i.e. along the platinum wire, when a violet 

 flame of varied intensity will easily be detected, occupying almost 

 all the region covered by the flame rising from the bead. 



As examples of the use of the scale above suggested, the following 

 results may be quoted. The burner used was 9 mm. in inner 

 diameter; the cone was 5 cm. high, and its top was 85 mm. above 

 that of the burner ; the flame was 18 cm. high, and 145 mm. above 

 the top of the cone. 



Grade less than 1,— Oligoclase, Ytterby. Flame just perceptible 

 in some experiments. Average of six published analyses gives 

 Kg = -62 per cent. 



