Boracic Acid in Minerals . 
125 
I described three different fluxes, by means of which the pre- 
sence of that alkali might be readily detected in spodumene and 
petalite. I had at first supposed, that any substance which en- 
abled those minerals to fuse readily before the blowpipe would 
answer the same purpose; and though this notion proved to be 
erroneous, it was not altogether , without its use. For among 
other re-agents that had been employed without success, I had 
used solid boracic acid, and mixtures of boracic acid with fluate 
of lime, and I observed that they uniformly tinged the point of 
the blowpipe-flame of a pure green colour, similar to what is 
seen during the combustion of alcohol in which that acid is dis- 
solved. Hence arose the question, whether the same colour 
might not be made to appear, when boracic acid exists in small 
quantity in minerals, so as to afford a sure indication of its pre- 
sence. That such a method is as yet a desideratum, will be ob- 
vious from the following observation, made by one of our first 
authorities on this subject. Berzelius observes, while speaking 
of boracic acid, “ I have not hitherto succeeded in my attempts 
to discover a test for this acid by the blowpipe, — a thing much 
wanted, since, as well as the fluoric, it often occurs in minerals 
in very small proportion, and frequently escapes detection in 
analyses made in the moist way 
When powdered boracite is moistened, and a particle of it is 
exposed on platinum-wire to the flame of the blowpipe, the cha- 
racteristic green colour appears. Datolite, as well as the Hum- 
bold tite of Salisbury-Craig, gives no green tint to the flame 
when treated alone before the blowpipe; but if previously moist- 
ened by sulphuric acid, the green becomes very distinct, — a fact 
noticed in general terms by M. Pfaff in his Analytical Chemistry. 
Bqracic acid has been detected in several varieties of tourmaline. 
Thus Arfwedson found about one per cent, of it in the blue 
tourmaline of IJton; M. Gruner discovered nine per cent, in a 
variety from Greenland; and, still more recently, Prof. Gmelin 
has detected the same acid in several other varieties of this mi- 
neral. When tourmaline is heated before the blowpipe, either 
alone or moistened with sulphuric acid, no trace of green ap- 
pears ; so that, if boracic acid is present, it cannot be detected 
f Berzelius on the Use of the Blowpipe, Children’s translation, p. 130. 
