Prof. E. J. Chapman on some Blowpipe Reactions. 463 



mineral substance of non-metallic aspect, in nine cases out of 

 ten, will be either a silicate, sulphate, phosphate, borate, car- 

 bonate, fluoride, or chloride — more especially if the streak be 

 uncoloured or merely exhibit some shade of green or blue, or 

 if the substance evolve no fumes when heated on charcoal. 



Simple fusion with phosphor-salt on a loop of platinum wire 

 serves at once to distinguish a silicate from any of the other 

 bodies enumerated above, as whilst the silicate is but slowly 

 attacked, these other bodies are readily and rapidly dissolved. 

 Among the latter, again, the carbonates are distinguished 

 without risk of error by the marked effervescence which they 

 produce in the bead by the evolution of carbonic acid during 

 fusion, the phosphates, sulphates, &c. dissolving quietly. The 

 reaction is quite as distinctive as that produced by the appli- 

 cation of an ordinary acid ; but, of course, it may arise in both 

 cases not only from a carbonate proper, but from the presence 

 of intermixed calcite or other carbonate in a silicate or other 

 body. It was by its use, upwards of twenty years ago, that 

 the writer detected the presence of carbonate of lime in certain 

 specimens of Wernerite (the " Wilsonite " variety), portions 

 of which had been previously analyzed without the impurity 

 having been discovered. It need scarcely be stated that the 

 test-substance must be added to the phosphor-salt, on the pla- 

 tinum loop, only after the quiet fusion of the flux into a trans- 

 parent glass. The reaction is, of course, manifested equally 

 well with borax*. 



On the Uselessness of Turner s Flux as applied to the Detec- 

 tion of Boracic Acid. — Many years ago (about 1827 or 1828) 

 Turner proposed, in examining a body for the presence of bo- 

 racic acid, to mix the test-substance with bisulphate of potash 

 and fluor-spar (in the proportions of 4J parts of the former to 

 1 part of the latter), and to expose the mixture on a clean pla- 

 tinum wire to the point of the blowpipe flame. Fluoboric acid 

 is thus produced ; and by its volatilization a momentary green 

 colour is imparted to the edge of the flame. Merlet recom- 

 mends the employment of 3 or 4 parts of this flux to 1 part 

 of the substance under examination. This test is much quoted 

 in blowpipe books and works on chemical analysis generally ; 

 but it is altogether superfluous. With borate of soda it fails 

 entirely, or yields very unsatisfactory results ; and although it 

 answers for most other borates and for borosilicates, it is use- 

 lessly applied to them, because these bodies colour the flame 



* It is sing-ular that tliis very marked and useful reaction should not 

 have been alluded to in any of the standard treatises on blowpipe prac- 

 tice. The only work known to the writer in which a passing reference is 

 made to it, is that of Hirschwald (Lothrohr- Tabellen), published in 1875. 

 The present writer called attention to it in 1871. 



