… technic” a higher department, providing for the more specialized wants
of each locality. This will be a work which no body is so well fitted to
undertake as the great Institute which has been a pioneer in higher
technical instruction. Such, it appears to us, is the true solution of
the question of the relations between the Charity Commissioners' scheme
and the City and Guilds of London.
One word of caution in conclusion. The new institutes should be allowed
to grow, and not be started on too ambitious a scale at first. Local
wants change, and the institutes should develop in harmony with their
changes. This is the lesson of the old Mechanics' Institutes and
Athenaeums. The lesson is repeated in the new experiments of Mr Hogg's
Polytechnic, and the People's Palace. We do not want to begin with
erecting huge shells of bricks and mortar, hoping that life will somehow
come into them after a time. The life first, then the buildings, to grow
as it expands and deepens — that surely is the law of nature. "Several
architectural white elephants" is the dismal but suggestive forecast of a
writer in the Charity Organization Review, on the supposition that this
law is violated. If these warnings are neglected, the promoters of the
movement will be merely courting failure, however good their intentions
may be. And they will have failed because "they were not poets enough to
understand that life develops from within."
ASSAYING.
Text-book of Assaying. By C. Beringer and J. J. Berringer.
(London: Griffin and Co., 1889.)
This text-book marks an important departure in the literature of assaying.
The authors abandoned the dreary details of the traditionary methods, and
attempt with success to rationalize the art of the assayer, rather than to
follow the usual course of reproducing "dry" assay methods and elaborate
classifications of processes the interest of which is only historical.
Assaying is here treated, in a broad sense, as the determination, by
analytical methods, of components of ores and of intermediate or finished
metallurgical products. Such compounds may be either of value in
themselves, or important from being valuable or injurious in the
operations of smelting, or in adapting the metals for use.
The methods of the authors, and the measure of success which they have
attained, may be fairly judged by their treatment of copper, lead, and
iron. Copper ores and furnace materials are still sold in the English
market by the "Cornish" assay. This antiquated method of assaying has
really no claim to retention, now that more trustworthy methods are well
known, and the authors give it but little prominence. They, however,
repeat the fallacious argument of its apologists by stating that "it gives
the purchaser an idea of the quantity and quality of the metal that can be
got by smelting." The Cornish assay does not deserve even this modified
approval, as the results it affords neither represent the actual amount of
copper contained in the ore, nor the proportion of metal which can be
produced by smelting, and several experts assayers, working on portions of
the same samples, will obtain results which vary in the most erratic way.
Fortunately for those who may be guided by this text-book, its authors
proceed to describe assaying processes which are really well calculated to
give trustworthy indications as to the quantity and quality of metal
obtainable from ores. These are to be found in well proved "wet" methods
of determining actual copper contained in ores as well as the components
that interfere with the extraction and the quality of the metal. In
describing these methods, ample information is given for the guidance of
the smelter under the varying conditions of the metal's occurrence. While
passing shortly over the Cornish assay, the authors judiciously omit such
clumsy "wet" methods of assay as the direct titration by cyanide of
potassium, which is retained in some recent books of standing, although it
has been abandoned by most skilful assayers. On the other hand, titration
by cyanide of potassium after separation of the copper from interfering
metals, and the assay by electrolysis, leave little to be desired in
rapidity and accuracy, and to these due prominence is given. Failing
reasonable manipulative skill, no assay can be accurate, and the
expertness demanded by those who conduct the "dry" or Cornish assay is not
more easily acquired than is the analytical skill needed for the better
"wet" methods. In an assay method giving accurately the amount of metal
actually present in the ore, the metallurgist has a sure basis for
calculation, the results of which can be brought under the control of his
experience as to the losses of metal in operations on a large scale. The
results of the Cornish assay, with all its inherent uncertainty, have
equally to be judged in the light of the smelter's experience as to what
the final "out-turn" will be. In lead, again, the dry assay is usually
treated in books on assaying with much elaboration, which is no longer
useful, if it ever was. It gives results that indicates neither the
actual amount of metal contained in the ore, nor the amount which will be
produced by smelting, and like the Cornish assay for copper is most
unsatisfactory for guidance in smelting. The wet methods of lead assaying
which are described are convenient and trustworthy, while the only
practically useful methods of dry lead assay are given in sufficient
details. In the assay of iron ores we find dry methods entirely omitted.
The wisdom of this cannot be doubted, for the want of exactitude which is
characteristic of the dry assay of copper and lead is still more marked in
the dry assay of iron. Processes of wet assay capable of giving prompt
and strictly accurate results are available, and these are fully described.
The plan of subordinating or ignoring unsatisfactory methods of assay,
while giving prominence to those which have proved to be trustworthy, runs
through the treatment of methods of assaying the other metals, as well as
estimating the components of ores which are not usually dealt with in
books on assaying. Among the latter are silica, the earths, sulphur,
arsenic, and phosphorus. These demand study by the metallurgist, to whom,
under either the necessity of "fluxing" them away, or of minimizing their
interference with the purity of the metals, their ready and accurate
determination is a matter of the greatest importance. The details of
assaying the precious metals, though hardly sufficient for adoption in the
assay of bullion in a mint, are all that is needed in a works.
The authors have clearly not been content to merely record published
processes, but in order to add to the completeness of their work have
given unpublished …...
