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daily ; from six to ten of these loads are weighed, and
large samples taken from each ; the accumulation of these
car-moisture samples gives the average daily moisture
sample. From the number of loads dumped, the average
weight per load, and the moisture per cent, is calculated
the number of dry tons treated daily.

The sand passes from the cars to the bins, and thence
by belt conveyors into a rotary distributor over the centre
of each vat. The stream of sand is sampled three times
an hour for nine hours, the time taken to fill a 400-ton
vat. This large sample is quartered down, and four assay
tons of the dried sample are taken for duplicate melts and
weighings of gold and silver. If the variation in the
weights of gold obtained from these two melts does not
exceed x/50 m.grm., the average is taken as the value per
ton of the tailings charged that day ; otherwise the assays
must be repeat^.

After treatment, 16 cores are taken from the residue in
the vat ; this sample, weighing several hundred pounds,
is in turn cored, giving about ao lbs., which is dried,
mixed, and quartered, for the final assay sample. If the
final weighings differ by more than 1/50 m.grm., the
assays must fa« repeated.

The monthly output calculated on the basis of the pre-
ceding determinations are shown in the upper line of the
accompanying figure, the gold being to the right of the
datum line, and the silver to the left.

The total amount of unprecipitated solution is mea-
sured, sampled, and assayed, as is also the precipitated
solution. The solutions are evaporated down to a small
bulk, a much larger quantity of the latter than of the
former being taken; a mixture of litharge, silica, and
charcoal added, and the whole heated till dry; after
cooling, carbonate of soda is added, and the whole placed
in a crucible, melted, and assayed. These solution assays
are of great praAical utility, not only as guides to the
efiSciency of the precipitation, but also as giving warning
of the presence of reducing material in any charge seve-
ral days before the residue from such a charge is available
for assay ; they are made primarily for these reasons.

The estimation of the values recovered monthly on the
basis of these solution assays is shown on the lower line
of the figure.

The monthly bullion assays are made with the usual
precautions, including determination of the cupel absorp-
tion, check for volatilisation of silver, &c., and are shown
in the centre line of the figure. A shortage of bullion is
usual in the first clean-up, the deficiency being made up
in the succeeding months.

The total value of gold and silver required by the daily
assays is 328,09621 dollars, and that adually recovered is
337*428*62 dollars, or an excess of 2*84 per cent over the
estimate — a highly satisfaAory concordance.



Ratio of the Atomic Weights of Hydrogen and
Oxygen.— A. Leduc— The synthesis of water by weight
has led the author to the conclusion that 15*88 is the exaA
relation between the atomic weights of oxygen and hydro-
gen. Another method, founded on the determination of
the densities of the two gases (both separate and mixed
together in the proportion to form water), has given a re-
sult (x5'868) distindly lower than that given above. This
latter result Is probably due to the increase of pressure
produced when 2 vols, of H are mixed with i vol. of 0.-«
Comfiis RfnduSt cxxviii., No. 29.



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Chemical Nbws,!
Jane 9. 1899. f



Detertninatum of Potash as Pcrchloraie.



269



THE DETERMINATION OP POTASH AS

PERCHLORATE.»

By F. S. SHIVBR.

Thb increasing um of potath salts for fertilising purposes
has made the determination of potash a question of prime
importance to the agricultural chemist.

The desire to devise a method at the same time rapid
and accurate has been manifested in many ways in the
past few years, especially in Gennany, the seat of the
great potash deposits.

The German chemists believe they have solved the
problem in the so-called Stassfurt method, which, as all
know, permits of the separation of the potash by platinum
chloride after previous precipitation of sulphuric acid by
barium chloride in slight excess, and in a strongly acid
solution. This method, with praAice, is quite accurate
and rapid, with a slight tendency, however, to high results
in my hands. It possesses little advantage over the
Lindo-Gladding method, in so far as rapidity and accuracy
are concerned.

The following determinations were made by the Stass-
furt method— potassium sulphate, C.P., and pNOtassium
chloride, C.P., were mixed with such impurities as to
imitate the composition of commercial sulphate of potash,
sulphate of potash and magnesia, kainit, and muriate.



Tablb I
K.SO4

uted.
Gnn.



Sulphate of potash 0*3284

Sulphateof potashl gg
and magnesia .. / ^

Kainit .. .. .. 0*1000



Muriate .



KCl
used.
Gnn.

0*2506
0*2522



K,SO.

found.

Gnn.
0*3291
03289
01863
0*1870

0*1003
0*1009

KCl

found.
Grm.

0*2498
0*25x4



Error on
K«SO«.
Grm.
+0*0007
+0*0005
+0*0007
+ 0*0014
+ 0*0003
+0*0009

Error on
KCl.
Grm.

-0'0008
-0*0008



Error on

K,0.

Grm.
+00004
+0*0003
+0*0004
+0*0008

+ 0*0002
+0*0005

Error on
K,0.
Grm.

-0*0005
-0*0005



The fadorused for converting potassium platinichloride
into potassium sulphate was 0*35694, which is praAically
the same as that recommended in the Stassfurt method,
viz., 0*357. The fador used for converting potassium
platinichloride into potassium chloride was 0*30557,
which is pradically the same as that recommended in the
Stassfurt method, viz., 0*3056. It will be seen from the
above results that the method is quite accurate, with a
tendency, however, to slightly high results.

In view of the increasing importance of the potash
determination, it is highly desirable that we should
possess a check method, rapid and accurate, based on
some other principle of separation than that with platinum
chloride.

All of our present methods for the determination of
potash involve the use of platinum chloride as a means of
final separation, and hence they are all subjeft to the
same general sources of error, such as solubility of the
platinichloride in the 80 per cent wash alcohol used, &c.

Of all the salts which potassium forms with acids, none
are as well adapted for furnishing the basis of another
process as the perchlorate, which is nearly insoluble in
strong alcohol.

As all the compounds which perchloric acid forms with
the bases other than potash and ammonia are soluble in
alcohol, we may readily deduce the basis of another pro-
cess. The determination of potash as perchlorate is an
old process due to S6rullas, who first noticed the insolu-
bility of the salt in alcohol, and to Schloesing, who made
it the basis of a new process. Schloesing's process, im-

* Jowmal ofth$ Amfricatffil^fmical Sociity, ui., No, x.



proved later by Kraut, has, however, not come generally
into use, since the same produces inaccurate results.

W. Wense {Zeit. Angew, Chem,^ 2891, 691 ; and 1892,
233) has made the process useful, since he diminishes
the solvent adtion of the alcohol on the perchlorate
through the addition of slight quantities of perchloric
acid. He describes the following course of procedure :^

The solution to be investigated is evaporated, after once
freeing it of sulphuric acid and non-volatile acids with
perchloric acid in a porcelain dish. In order to wash the
perchlorate easily, it is desirable to produce the same in
a eranular condition. This is attained by warming the
solution containing the potash on a water-bath before
adding the perchloric acid, which must be run in drop by
drop. In all cases there are used about one and a half
to one and three quarters times the amount of perchloric
acid necessary for the decomposition of the salt present.

After the addition of the perchloric acid, the solution
is evaporated until all odour of hydrochloric acid or other
volatile acids has disappeared. For washing the precipi-
tate 96 per cent alcohol is used, to which two-tenths per
cent of its weight in perchloric acid is added.

The residue from the evaporation is treated with 10 c.c.
of the alcoholic wash solution, which may take up only
i/2o,oooth of a part of potassium perchlorate, and the salt
mass is then broken up with a stirrer.

Decantation is performed through a weighed filter,
which has been previously dried at 120 — 130" C, when
the breaking-up of the salt mass is repeated, and the
residue again treated with the alcohol wash solution.
The precipitate is then brought on the filter, and freed of
the adhering perchloric acid solution by washing with a
few c.c. of pure alcohol. The filter is then pressed be-
tween folds of filter.paper, dried for twenty-five minutes
at 120—130° C, and weighed.

One part of potassium perchlorate corresponds to
0*5382 part of potassium chloride, and 0*6289 part of
potassium sulphate.

According to the author, the whole washing with a good
pump occupies only a short time, and requires 50 to 70
grms. of alcohol. If the substance to oe investigated
contains sulphuric acid, the same is to be removed in the
usual way by barium chloride previous to the determina-
tion of the potash. The author, who used the method in
the investigation of potassium chloride, C.P., commercial
muriate, kainit, and carnallite, obtained — according to the
analyses reported—very favourable results.

R. Caspari (Ztit. Angew, Chem,, 1893, ^^) recommends
colleAing the potassium perchlorate in tubes containing
asbestos filters, and subsequent drying for twenty minutes
at 230—150° C. The lubes are allowed to cool in a
desiccator or in the air and then weighed.

According to Caspari, the method is applicable for
fertilisers, ashes, and the like, in the presence of phos-
phoric acid, alkaline earths, iron, alumina, and manganese,
if the following method of procedure is adopted : —

After the removal of sulphuric acid, the hydrochloric
acid solution is evaporated for the purpose of getting rid
of the free acid, the residue stirred with 20 c.c. of hot
water, after which perchloric acid is added in quantity not
less than one and a half times that necessary for the
decomposition of all salts present.

The solution is now evaporated with frequent stirring
to a syrupy consistency, some hot water is again added,
and the solution evaporated still again with occasional
stirring until the disappearance of all odour of hydro-
chloric acid, and till the appearance of white fumes of
perchloric acid. An evaporation of large quantities of
perchloric acid is to be avoided ; if this takes place, more
perchloric acid is to be added.

The cooled, more or less syrupy, contents of the dish
are well stirred up with about 20 c.c. of wash alcohol (96
per cent alcohol containing two-tenths per cent perchloric
acid), taking care, however, not to reduce the potassium
perchlorate to a fine powder. After the alcoholic solution
has become clear, it is decanted through the asbestos



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Determination 0/ Potash as Perchlorate.



1 June 9, iSgg.



filters, the washing repeated with the same quantity of
wash alcohol, allowed to settle, and decanted again.

The residue remaining in the dish is freed of alcohol
by gently warming, evaporating again with about three-
tenths grm. of perchloric acid and a little water, and washing
the cooled mass with several c.c. of alcohol, with which it
is also brought into the filters and the perchlorate in the
tubes finally covered with a little pure alcohol. The
potassium perchlorate obtained in this way contains,
according to Caspan, no phosphoric acid, or only slight
quantities of the same ; on an average only 0*00057 grm.
phosphoric acid.

In the separation of sulphuric acid, Caspari seeks to
avoid, as much as possible, a loss of potash, since he pre-
cipitates in a strong hydrochloric acid tcdution at the
boiling temperature with a concentrated solution of
barium chloride made acid with hydrochloric acid. Ex-
periments of the author prove also the applicability of the
method in the presence of other acids not volatile on the
water-bath, as chromic acid, and also boric, tartaric, and
oxalic acids. If ammonium salts are present, they are to
be removed either with soda-lye or milk of lime, by gentle
heating or through careful ignition.

A. Kreider {Am, Journ. Set,, xlix., 443) has followed
the method as described by Caspari, and has obtained
very satisfadory results. Kreider found the Gooch
crucible preferable in the filtering of the perchlorate. and
recommends the same instead of the tubes proposed by
Caspari. In the presence of phosphoric acid, the previous
separation of which is not necessary, it appeared
advisable, according to Kreider's experiments, to allow
the perchlorate precipitate to stand with an excess of
perchloric acid before treating with alcohol.

Six determinations made of potassium unmixed with
other bases or non-volatile acids gave the following
results : —

In two cases the theoretical amount of potash (KaO)
was recovered as perchlorate ; in three cases there was a
loss of o'oooa grm. ; and in one case a loss of 0*0003
grm. ; one-tenth grm. of potassium chloride was operated
on in all cases. In order to repeat Kreider's work, and to
ascertain the accuracy of the process, the following work
was undertaken. A solution of chemically pure potassium
chloride was prepared by dissolving x-0005 grms. in 200
c.c. water, i c.c of the solution was found to contain
0'005 grm. potassium chloride, aliquot portions being
measured from a burette, evaporated, dried, and weighed.

In all the work here reported, the method as proposed
by Caspari, with the use of the Oooch crucible, as sug-
gested by Kreider, was employed.

However, in the first three experiments reported, the
perchlorate was colleded on paper filters as suggested by
Wense, washed in the usual way, dried, and the per-
chlorate dissolved in hot water, and the solutions evapo
rated to dryness in platinum dishes and weighed.

In all cases the weighed perchlorate was a little dis-
coloured, due to the fad that the paper filters had been
aded on to a slight extent by the perchloric acid, causing
them to char a little around the edges during the process
of drying. In the subsequent leaching with hot water,
some of this carbonaceous material dissolved, and went in
solution with the perchlorate.

The results obtained by weighing in dlihet as above
described were as follows :^



Tablb II.



I.

II.

III.



KG I Bqoivs-

■olution lent to

used. KCl.

C.c. Grm.

6'a 0*0310

8*1 0*0405

5*0 0*0250



KCl
foood.
Grm.

00310
0*0411
0*0253



Brroroa
KCl.
Grm.

+0*0000
+0*0006
+0*0003



Brroron
K,0.
Grm.

+0*0000
+0*0004
+0*0002



Average .» 0*0322 0*0325 +0*0003 +0*0002



It will thus be seen that the average error in these
determinations is 0*0003 grm. KCl ; it is possible that this
slight plus error is due to the slight discolouration already
noticed, and the weighing in dishes is not to be recom-
mended, thouffh the results obtained are sufficiently
accurate for all praaical purposes. In the other expert*
ments which follow, the potassium chloride was weighed
out diredly for analysis, and the perchlorate was colleded
always in a Gooch crucible.



I.

II.

III.

IV.

V.

VI.

VII.





Tablb III.










Error on


Brroroa


KCl used.


Kafouod.


KCl.


K,0.


Grm.


Grm.


Grm.


Grm.


0*0848


0*0859


0*00X1


+0*0007


0*0217


0*0217


0*0000


O'OOOO


0*04x9


004x3


.0*0006


—0*0004


0*1007


o*xoo9


+0*0002


+ 0*000 z


0*1003


o*xox5


4.0-00x2


+00008


0*xoz6


0-10x5


— 0*000 X


-0*0000


0*02:7


002x0


—0*0007


— 0*0004


00675


00677


+0-0002


+ 0-OOOZ



Average.



In the above determinations No. x was among the first
made, and it is possible that the slightly high results ob-
tained were due to lack of familiarity with the method.
Excluding No. I., the average would be as follows :»

KCl nted. KCl lonod. Brror on KCl. Error on K,0.

Grm. Grm. Grm. Grm.

0*0647 0*0647 0*0000 0*0000

It would thus appear that the determination of potash
as perchlorate in mixtures free from other bases and non-
volatile acids, is quite accurate, equally as much as the
determination by platinum salt.

After nitrogen and phosphoric acid, potash is the com-
pound one has mostly to determine in fertilisers, plants,
and soils. The potash is usually combined with sulphuric,
nitric, or carbonic acid, and more rarely with phosphoric
acid.

These salts are almost always associated with alkaline
salts and the alkaline earths. It is now therefore a
question of the applicability of the perchloric acid method
to the determination of potash when associated with these
other bases and non-volatile acids, such as sulphuric and
phosphoric acid. In regard to the bases, it has been con-
tended by some that magnesia is a disturbing element in
the determination of potash by perchloric acid.

Schloesing has shown, however, that in the following
mixture, after the removal of sulphuric acid by barium
chloride and conversion of bases into perchlorates, the
magnesia did not have any disturbing efifed.

Potassium chloride 0-0835 grm.

Magnesium sulphate • . . . . . 0-5740 „

Sodium chloride .. .. .. .. o*x298 „

Calcium chloride • 0*2330 „

In this mixture there was recovered, by proceeding at
above stated, 0*08x4 grm. potassium chloride. Kreider
has also shown that magnesia has no disturbing efife^
He treated o*X500 grm. magnesium carbonate with per-
chloric acid, evaporated till fumes of perchloric acid
appeared, and cooled, when magnesium perchlorate crys-
tallised ; on treating this with alcohol, a perfeaiy clear
solution was obtained. It was also thought that it was
necessary to remove all non-volatile acids previous to the
separation of the potash as perchlorate. Caspari and
Kreider have, however, shown that it is only necessary to
remove sulphuric acid. In order to secure a nearly com-
plete separation of phosphoric acid from the potassium,
Kreider has shown that a considerable excesa of per-
chloric acid should be left upon the potassium perchlorate
before it is treated with the alcohol.

Kreider's results pn % mixture cpntaining— >

Digitized by VriOOQ IC



Obbmical Kiwi, I
Jane 9i 1899. I



Presidential Address to the Iron and Steel Institute.



2^1



Potatsium chloride o'l grm.

MagDetium sulphate 0*13 „

Aluminum sulphate •• •• .. •• 0*05 „

Sodium phosphate • • 0*4 „

Calcium carbHonate 0*13 „

Ferric chloride •• .. •• .. .. 0*05 „

Manganese dioxide . • 0*05 „

were quite promising, as will be seen from the results
reported in the Amtrican yournal ofScitttci, xlix., 448.

The method as modified by Caspari and Kreider is
quite promising, and I hope in the near future to do some
further work on the determination of potassium associated
with other bases and non-volatile acids.

(To ba continued).



PRESIDENTIAL ADDRESS

TO

THE IRON AND STEEL INSTITUTE.

By PaoFBSBoa Sia W. ROBBRTS-AUSTBN, K.C.B.,
D.C.L., F.R.S.

(Condoded from p. 259).

1885-87. In no other branch of modern scientific litera-
ture than that of metallurgy does one individual stand
far above his contemporaries and absolutely dominate hit
subjeA as does Dr. John Percy. It may be fairly claimed
that he did this, for he truly represents the progress of
metallurgical literature during the nineteenth centurv.
He was also the century's greatest teacher; he found
metallurgy praAised in this country as an empirical art,
His splendid works contain a record of its progress ; his
leAures at the Royal School of Mines secured it a scien*
tific basis, and he trained a body of workers in whose
hands the immediate future of metallurgy still, to a great
extent, rests. To few men does the nation owe more
than to our President of 1885-87. The educational work
Dr. Percy began is being adively developed. As regards
its progress in the future—which is of vital importance —
there seem to me to be no requirements that may not be
abundantly met by the extension of existing institutions.
The establishment of a Board of Mining and Metallurgy
in connedion with the new Teaching University for
London, would, I am satisfied, greatly sitimulate in-
struAion in these subjeAs.

zSBy-Sg. Daniel Adamson will be known rather as a
mechanical engineer, and the originator of the Manchester
Ship Canal, than as a metallurgist. His Presidency of
this Institute is, however, remarkable for his strenuous
advocacy of the use, not only of steel as distinguished
from iron, but that for definite purposes steel of a definite
degree of carburisation and suitable composition should
be employed. He also eloquently urged that the steel at
all stages of its manufadure in its varied applications
should receive suitable thermal treatment. He strongly
advocated the use of steel for the manufadure of boilers,
and he pointed out that by the use of steel rails and
weldless solid rolled steel tyres, the saving to railway
shareholders amounted to about £'3.120,000 sterling per
annum, while the safety and security of the travelling
public had been correspondingly increased. No better in-
dication of progress in the decade ending 1889 could well
be given than this.

1889-91. The vast advance during the century in the
applications of iron and steel in the manufadure of ma-
chinery, and more especially to locomotives, is fittingly
represented by Sir James Kitson. We, moreover, owe
him a deep debt of gratitude for the admirable way in
which he represented the Institute by presiding at the
Autumn Meeting of the Institute in Paris in 1899, as well
as during the arduous but most remarkable visit to the
United States in 1890. Sir James, by his unflagging vigour
and nnfiiiling tad, did much %o cement the friendship of



workers in iron and steel, both among our neighbours in
France and our kinsmen in America. I will only add that
he has persistently advocated the use, and has well main-
tained the reputation, of that admirable material, '* best
Yorkshire iron."

1891-93. One of the most noteworthy events in the
metallurgical progress of this country was the acceptance
by Sir Frederick Abel of the post of Chemist of the War
Department. The teaching of such illustrious men as
Berzelius, Heinrich Rose, and Liebig was just in process
of thorough application in this country when Abel left our
matchless teacher Hofmann to take his place among the
earliest trained analytical chemists whose aid was sought
by the ironmaster. He thus became, as it were, the
'* Patron " of works chemists. They are men on whose
patient, monotonous, and often inadequately recompensed,
labours the quality of British iron and steel has in no
small nieasure depended, and I am glad to have this op.
portunity for offering my brethren, the chemists in works,
a respedful tribute of admiration. The magnitude of
their work may be gathered from the fad stated in the
Journal of our Institute, that in one basic steel works
over 110,000 determinations are made in a single year by
three chemists and six assistants. Of Sir Frederick's
numerous investigations, the one which appeals to us
most closely is that which definitely settled, as FesC, the
composition of carbide of iron.

Lord Herbert of Lea, who was several times Secretary
for War and was in office soon after Sir Frederick was
appointed to Woolwich, appears to have been advised
that '* steel was wholly inapplicable for the manufadure
of ordnance." When we consider what the nature of our
present war material is, and refled how large a part Abel
played in its introdudion and adoption, it will be evident
that any further comments of mine as to the value of his
labours would be unnecessary. He is himself a most
adive exponent of the truth ** that the intimate blending
of science with pradice lies at the root of all industrial
progress and success.**

1893-95. ^ ^^ quoting from an American source the
testimony that " an historical sketch of the perfeding of
modern processes of steel manufadure would afford the
best glimpse that could be given of the career of Edward
Windsor Richards.** He was among the first to appre-
ciate the need for reversing mill-engines, and an early
one ereded by him is still at work at Ebbw Vale. He de-
signed the works of Messrs. Bolckow, Vaughan, and Co.,^
at Middlesbrough, the largest in the kingdom, and as



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