59
Hon. D. M. S. S.,
A stack of 1 cwt slabs of tin is sampled
by taking 10% plus 1 of the slabs from the pile at random.
At the time, the Sampler takes a diagram of the position
of the sampled slabs. See attached diagram.
These slabs are then drilled in accordance
with the sketch. The drillings are wrapped, sealed and
brought to the Laboratory by the Sampler.
The drillings are melted up under the su-
pervision of the Analyst who later does the determination.
The method used is described in Parry's "The Assay of Tin
& Antimony published by the "Mining Journal" Office 26
Queen Victoria Street E.C., on page 23 onwards. A button of metal weighing about 60 grams is obtained by pour ing
part of the melted drillings into a hemispherical mould.
Duplicate determinations are carried out on 1 gm. portions
of the filings from this button. At the same time duplicate
portions of 1 gm. pure tin (99.97% pure) are treated in
exactly the same way. The percentage of tin is given by
Titration of sample
Titration of pure tin X 99.97
Tin.
A tin that fails to assay 99.1 by this method is not passed
as a No. 1 Chinese Tin.
In the case of 28 lbs slabs a similar pro-
cedure is carried out except that the slabs are drilled
completely through at varying places with one hole per slab.
li Jackson.
Government Analyst.
28/ 2 / 35.