MINERALS AND GEOLOGY OF CANADA. 17 
cases the actual amount of a metallic or other ingredient previously 
ascertained to be present in the substance under examination.* 
In the employment of the blow-pipe (in conjunction with external 
characters) in the simple determination of our Canadian minerals, 
we are never compelled to resort to more than two experiments: the 
fusion-trial, and the water-test. The student will find it of advan- 
tage, however, to study in addition the reactions of the more common 
metals and metallic oxides as given in special works on the Blow- 
pipe. ‘To describe these reactions in the present essay would extend 
the subject much beyond its allotted limits. 
The Trial of Fusibility.—In order to ascertain the relative fusibility 
of a substance, we chip off a small particle (the smaller the better) 
and expose the point of this to the extremity of the blow-pipe flame 
—holding the test-fragment in a small pair of tongs or forceps with 
platinum tips ;+ or supporting it, if it be of a metallic aspect or of a 
certain weight and exhibit at the same time a coloured streak, on a 
piece of well-burnt pine charcoal. The particle thus exposed to the 
flame ought not to be larger than a small carraway seed. If it be 
fusible, its point, in the course of ten or fifteen seconds, will become 
rounded into a bead or globule. The proper method of blowing can 
be acquired by half-an-hour’s practice. The cheeks are to be filled 
with air, and this is to be urged gently and continuously down the 
tube by the compression of the cheek muscles, the operator breathing 
at the same time (if he require to do so) through his nose. By a 
little practice this becomes exceedingly easy ; and the blowing need 
never be kept up (at least in experiments of this kind) for more than 
a quarter of a minute at atime. A thin splinter will exhibit signs 
of fusion in ten or twelve seconds, or not atall. The use of the 
instrument, therefore, is easily acquired, and is in no way injurious 
to the health. 
Thus treated : 
(a) The test-fragment may ‘‘decrepitate’” or fly to pieces. 
Example, most specimens of galena. In this case, a larger fragment 
* See, for example, a paper by the author “on the Assaying of Coals by the Blow-pipe,” first 
published in this Journal; Vol. III., page 208. Also Plattner’s “ Probirkunst mit dem 
Lothroéhre.” 
+ These forceps may be obtained from any dealer in chemical apparatus. For simple expe- 
riments they may be replaced by a strip of thin sheet ircn bent into the form of a pair of 
nippers or tongs. Some twine or silk must be twisted.round the middle part to prevent the 
fingers from being burned. 
Vou. V. Cc 
