Section III, 1889. [ 13 ] Trans. Eoy. Soc. Canada. 



IV. — Notes on some Unexplained Anomalies in. the Flame Reactions of certain Minerals 

 and Chemical Bodies. By E. J. Chapman, Ph.D., LL.D. 



(Read May 9, 1889.) 



The brief notes embodied in this communication refer to some anomalous points in 

 the flame reactions and spectra of certain mineral bodies, at present of doubtful explana- 

 tion or which remain altogether unexplained. Attention is called to these anomalies in 

 the hope of eliciting a clue to their satisfactory interpretation. 



(1.) AxiNiTE AND Tourmaline. — Substances in which boracic anhydride is present, 

 commonly impart, it is wellknown, a green colour to the outer envelope of the Bunsen or 

 blowpipe flame. In the case of Axiuite, a silicate containing between 5 and 6 per 

 cent, of B-O", the green flame-coloration is always manifested; but in that of Tourmaline, 

 a silicate in which the amount of B"0' exceeds 9 or 10 per cent., no trace of colour is 

 im]Darted to the flame unless the mineral be treated with special reagents.. There does 

 not seem to be any ready explanation of this anomaly. The amount of silica in each 

 species is comparatively low, and not far from coincident. Axinite, it is true, is an 

 alumino-calcareous, and Tourmaline an alumiuo-magnesian silicate ; but the presence of 

 lime in one case, and its absence in the other, hardly seems sufficient to account for the 

 phenomenon. In the calcarous species Datolite, the coloration of the flame is strongly 

 marked ; but it is equally well displayed in the magnesian Boracite. All the later 

 analyses of Tourmaline show a small amount of fluorine, aA'eragiug 0'65 to 0'70 per cent., 

 and this should assist in bringing oiit the flame reaction. In the analyses of Axinite, 

 fluorine has not yet been recorded, but I have recently found distinct indications of its 

 presence in the decomposition of the glass obtained by fusion. 



(2.) Apophyllite and Orthoclase. — These two potassic silicates are here placed in 

 juxtaposition, in order to show the influence of fluorine in flame reactions. Apophyllite 

 contains, or rather yields to analysis, between 5 and 6 per cent, of potash ; whilst Ortho- 

 clase contains practically lY per cent, of that component. When moistened, in powder, 

 with hydro-chloric acid, Apophyllite shows in the spectroscope the red line of the potas- 

 sium spectrum very distinctly and persistently ; whereas Orthoclase, with more than 

 three times the amount of potash in its composition, does not under this treatment reveal 

 the slightest indication of potassium. The apparent anomaly may perhajjs be explained by 

 the assumption that the potassium in Apophyllite is not in an oxidized condition, but in 

 combination with the 29 per cent, of fluorine present in the mineral, forming 6'40 per 

 cent. KF. This view of the composition of Apophyllite is not adopted, however, by all 

 mineralogists. The small amount of fluorine is regarded by some as apparently replacing 

 oxygen, or is looked upon as of little practical moment. In the third edition of Tscher- 

 mak's " Minéralogie," issued within the present year (1889), for example, the chemical 



