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84
E.
Journal of the Chemical, Metallurgical and Mining Society of South Africa.
[Nov.·Dec., 1944
on Some, Sulphide Minerals from the Far East Rand;
~endelssohn-Notes
The features which distinguish quality
control from all other methods--':and all four
features must be present-are:(I) Regular measurement or gauging of
relatiyely small samples according to
a predetermined plan:
(2) Instant charting of the results of the
above' operations.
(3) Control limits fixed by statistical
method and quite independent of the
engineering or specification limits.
(4) Constant exhibition of the charts
where the production force can easily
fulfil its duty of knowing' and
understanding the information on
them and, in co-op~ration with the
inspection force, of taking prompt
action.
Quality, control ~laims gradually to get
rid of.all those variations due to assignable
causes, leaving only the variations due to
chance, that is,' those which must be
expected. When all the plots . are within
the control lines the product is said to be
in a "state of control," but should any
plots appear outside the control lines, they
are action points which may call for prompt
investigation to remove the assignable cause
of the variation.
When the "state of
control" exists, no higher degree of
uniformity can be expected from the process
in use. Quality control is not difficult or
troublesome; it can easily be introducl'ld
for one or many cases as an overlapping
operation, and this overlap need not last
very long. It requires no additional plant
and, in the end, actually saves labour. It
0
.' ought to be introduced to assist in com bating
the many, hindrances to which manufacture is now subject. Its 'use is preeminently to reduce the amount of rejected
work, and all, which that implies, and to,
improve the quality of any product.
While the statistical foundations are ,of
great intere~t, yet so m~ch hag been done
that these foundations may now be taken
for granted. Pr,oduction engineers can do
a great deal to put the nTatter to test and
into operation by study of the simple and
practical British Standard No. 1008-1942
or thaAmerican War Standard ZI-3·42.*
Quality control charts furnish good
evidence of the quality of a firm's manufacture and inspecti_on. When a state of
control is reached it is believe,d that at
least some of the service inspection departments will accept this as' justifying them in
leaving inspection to the firm.
In this connection Mr. Ford has told us
a'Qout the methods he has adopted for'
improving the output of the labour force
on the mines. I would like to ask him to
tell uS how' this is recorded, whether they
US!) charts similar to those used by the
quality controls, or whether they have some
better method of-recording the output of the
v;arious'departments.
The President: Now, gentlemen, we
have a further paper for presentation this
evening, a paper by Mr. E. Mendelssohn
, (Visitor), entitled "Notes on Some Sulphide
Minerals from the Far East Rand." May I
ask Mr. Mendelssohn to present his paper.,
NOTES ON SOME SULPHIDE, MINERALS FROM THE
F~R
EAST RAND.
By E. MENDELSSOHN (Visitor).,
During the past ff?w years a num,ber of:
unusual sulphide minerals' have be,en found
in the mines of the Far East! Rand, particularly in the East Geduld Mine, which
have not been previously recorded as
occurring on the Rand. Tlie purpose of this
note is merely to place on record this
occurrence, and to describe some of the
properties of theniinerals found, so that
eventually by the collection of data of this
kind, we may be able to' obtain 'a more
complete list of' the minerals, that occur
in the ,Witwatersrand mines.
Orily a few specimens have been obtain~d
and these would never have been noticed
or collected had it not been for the enthus-
* The S.A. Standards Institution has decided to
advocate the adoption of Statistical Quality Control
in this country, and has applied for a . number of
copies of ZI·3.42. The Secretary, Mr. J. Crompton,
P.O. Box 3293, Johannesburg, will be pleased to
register applications for these.
Reproduced by Sabinet Gateway under licence granted by the Publisher (dated 2012)
Nov.-Dec., 1944J Journal of the Ghemiclll, Metallurgical and Mining Society of South Africa.
·E. Mendelssohn-Notes on Some Sulphide Minerals from the Far East Rand.
iaf;lm of Mr. Flugge-de Smidt, who has
constantly taken the greatest interest in
the mineralogy of the local mines; Through_
his kindness a number of these specimens
have been presented to the UniversityMuseum, and the author would like to take
this opportunity of expressing to ,him the
thanks of the University for the numerous "
specimens he has presente~,
DESCRIPTION OF MINERALS.
Gersdorffite.
Well-developed crystals of gersdorffitewere found in a vug in a quartz vein.
Associated with the gersdorffite were small
amounts of chalcopyrite and pyrite., The
crystals were octahedrons, silver-white in
colour and up to a maximum length of
about 10 mms. On some crystals a small
development of cube faces was observed,
and in ~me crystal the suggestion of the
r hom bdodecahedron.
Gersdorffite has been found at a number of
localities on the East Geduld Mine, in one
instance associated With a spectacular
concentration. of gold, in a quartz-apatite
vein.
•
I
Some of the purest -crystals were used
for analysis, which was done by the late
H. R. Adam and gave the following result ; -Ni
-As
S
Fe
Cu
.. .
.. .
.. .
.. .
andSb
31·7
44·5
19·8
3·1
... traces
This corresponds very closely to published
analyses of gersdorffite from other locailities.
Oubanite. - (C~ Fe 2 Sa)
This mineral, also know.n as chalmersite,
it is suspected is rather more widely
distributed, as after its· discovery on East
Geduld, it was identified in specimens
.from other mines of the Witwatersrand.
It seems to occur invariably .in druses in
quartz veins; where it is usually associatedwith crystals of quartz, pyrite, pyrrhotite
and sQmetimes chalcopyrite. In size the
crystals of cuba.nite reached -a maximum of
about 20 mms., and in shape were of two
0
85
more or less distinct habits,_ namely, as
thin tabular plates or as long slender prisms.
Unfortunately, the faces of the cry'stals
were mostly strongly striated, particularly
in the prismatic type, and only very few
crystals - were foun~ - suitable for goniometric measurements, and these were very
small:
- .
Clinographic projections of the two main
types are shown in Figs. 1 and 2.
'In the tabula~ type (Fig. 1) th~ dominant
development is parallel' to the brachypina~
coid (010), giving rise to a very thin plate
with the other _forms present as minute
strips along the edges.
.
This habit is similar to that of some
crystals of this mine.ral described from the
Morro Velho Mine, in Brazil. *
The brachydome (034) on the East
Geduld crystals, however, appears to be a
new form nut previously (described and has
been lettered k.
.
In t~e prismatic type (Fig. 2) very few
crystals. were found with terminal faces,
as most of the crystals were broken, due
to the brittle character of the mineral,
and the fact that the crystals were developed
as thin needles.
Even where terminal
faces were found, usually only a base (001)
and· one or two other faces were present.
The prism faces _were almost invariably
deeply striated, due to oscillatory combination.
The general habit resembles
some types from the Morro Velho occurrence,
but the cry'stals from Brazil are much
richer in the number of forms present. One
fonn shown in Fig. 2 is the pyramid (112)
which has been lettered v and which has also
not been previously found jn this mineral.
Specimens of the mineral were polished
for microscopic examination, and were
found to agree ~n all physical properties
and etch reactions given for cubanite in the
standard texts.
The complete list of the forms found in the
East Geduld . crystals is c (001), b (010),
a' (100), m (110), 1 (130), f (012), g (011),
-k (034), v (112).
* Palache, C.: "Mineralogical Notes 3. Crystal
Form of Chalmersite." Am. Jour. Science. Series
IV, Vol. XXIV. 1907.
\
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86 '
Journal of the.Chemical, Metallurgical and Mining Society of South Africa. [Nov.-Dec., 1944
E. Mendelssohn-Notes ·on .s.om~ Sulphide Minerals from the. Far East Rand.
.
Millerite (NiS).
. Small hairlike .crystals of this pale
brassy coloured sulphide were founp. along
cleavage 'planes in some specimens of
sericitized quartzite. The. crystaJs are so
thin that it is rather remarkable that
they were ever noticed, in the course of
mining operations. The average width· is
about 0·1 mm., and no crystal has been seen
exceeding 0·2 mm. in thickness. . T4e
length goes up to 2 cms., so that the proportion of length to thickness is usually
of the order of about 100 to 1. Individua,l
forms are too small for measurement, not
c
.::;::0:
t
m
b
(.
b
m
FIGI
-"
.....
cS:---=m:--c..----?::1---1. .
A
B
c.
FIG .3
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Nov.·Dec., 11)44]' Journal of the 'Chemical, Meta.llurgical and Mining Society of South'Africa.
E. Mendelssohn--Notes on 'Some Sulphide Minerals from 'the Far East Rand.
reflecting sufficitmt light for goniometric
measurements, but by. the :shape and
common mode of gro;wth ,of millerite, it is
evident that the_ crystals' are elongated
parallel to the vertical axis. The faces then
, become dominantly those of the hex~gonal
. prism:
,
Minute terminal faces' can .be seen on a
few crystals,. and these pro ba bly represent
the rhombohedron (lOll).
In many cases the crystals, were found
with a distinct bend or curve along the
length. This is common in millerite where
it occurs in capillary· form, and the mineral
is said to be' elastic where developed with
this habit. In the mineral examined, however,' this bending appears t<?, be more an
irregularity in growth, as the mineral is
now permanently d«{formed and does not
appear to have been subjected to any strain.
Small cubes of pyrite are often seen
growing on the sides of the needles' and
occasionally small hexagonal plates of
pyrrhotite. The' base of a crystal is sometimes found firmly attached to such a
pyrrhotite plate.
Microche:n;tical analysis 'proved that the
only important metal present is nickel.
87
fully described from various localities, so
that _a short description' of the principal
ha bits of, the crystals is only necessary:
In practically all the crystals, irregularities
of growth are comm<?n, resulting-in' curved
faces and'striations. Many' of,the specimens
consist of irregula~ intergrowths' and
~parallel growths of a number of separate
individuals., In Fig. 3 the more common
types .are illustrated. Crystals occurring
with the habit shown in Fig. 3A are often
very thin plates, and these plates may be
curved due to irregularity in growth. A
number of plates have sometimes grown
together to form a single complex individual.
A crystal of pyrite with this same tabular
habit has been found and it is clearly
pseudomorphous after pyrrhotite.
The crystal' shown in. Fig. 3D is deeply
grooved horizontally, due to oscillatory
combination between the prism m and the
pyramid U.
.
The following is a complete list of all the
forms which were found to be present~
'C (0001),(1010), z (2021), and u (4041).
A few carefully chosen crystals from
East Geduld Mine were analysed by Dr. B.
Segal.and gave the following result. '
m
Pyrrhotite.
Pyrrhotite is a mineral ,that is foundfairly commonly in the Witwatersrand
mines, and its occurence has been known
for a ,long time.
The only purpose of
describing it in this -paper, is to give some
details of the crystallographic forms which
are commonly developed. More recently
its associa.tion, in certain cases, with gold
values, has, been investigated* and the
pyrrhotite described in that article can be
regarded as a normal constituent 'of' the
banket which was examined, whereas the
crystals referred to here occur mostly
in druses in quartz veins, and it is suggested
that the two' types of pyrrhotite, are not
necessarily of the same age or origin.
Crystals showing a 'considerable variation
in habit were examined. No unusuaJ or
comparativdy rare forms were found however, and similar types have already been
* Pelletier, R. ,A., 1940: ' "Pyrrhotite as an
Enriching Factor in Rand' Ores." Jour. Met. and
Min. Soc. S.4., 1940. .
Fe
S
Per
Cent.
... ' 63·72 '
... 36·24
99·96
Fe: S=I·141 : 1'130.
This composition corresponds closely to
the pure end member of the pyrrhotite
group. which is known as troilite, and is
usually, only found in the iron meteorites
where an excess of Fe over S is present. It
has been recorded, however, as occurr.ing in
terrestrial deposits in California.
As already inp,icated, however, it is' not
suggested that all the pyrrhotite in the
Rand conforms to this composition, and it
is, in fac~, more probable that the pyrrhotite
found in Banket has the more general
'
\ composition of FenSn+1 •
Tpe four sulphide minerals described
, were spec~roscopically analysed through ,the
kindness of Dr. Ahrens,· of the Mineral.
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88
. Jou.malof the Chem(cal,MetalluTgical and Mining Society of South Africa. [Nov.·Dec.,
E, Mendelssohn-Notes pn Some Sulphide Minerals from the Far. Edst Rand .
Research Laboratories, who reported. as
foHows : /
Ag.
Cu.
Ni
Co
As
Sb
Fe
Gers· '1
/ pyrrhO./
dorffite. Cubanit~
tite. Millerite
...
.. ,
'
...
xj.
x-xx
xxxxx
xx
xxxx
...
xx
...
...
...
xx
xxxxx-Predominant;
xxx-Small Quantity;
Trace.
-
xxxx
x-xx
x?
-
xxxx
x
x
--
xxxx'
-
-
xxxxx
-
-
xxxx-Considerable;
xx-Trace; x-Minute
The President: To the average miner, .
a description of our reef here is. that it is a
conglomerate of pebbles of quartz and
quartzite,. cemented in ,a matrix of grains,
also of quartz with iron pyritis and smaller
quantities of other metallic -minerals.
As .long as these other . minerals. have' no
nuisance value they do not usually interest
him a. great deal, and as long as there is a
sufficiency: of pennyweights of gold present
he leaves it at that: Few mines are fortunate
to have an enthusiast like our Mr. Fluggede Smidt, with the qualifications anp. the
opportunity, ,time and energy to look for,
and collect, specimens of unusual minerals.
It is just as, well that we ~re pulled up in
our ignorange. occasionally in, 'order to
realise. that our reef body may contain
something more than gold ..
We are greatly indebted to 'Mr. E.
Mendelssohn for presenting to this Society
,these most interesting notes on some
sulphide minerals from the Far East Rand.
Although the occurrence of most of these
minerals maybe extremely small and they
may' not have' any appreciable adverse
effect 'on gold extr)l.ction, it .is, n(lvertheless,
of considerable value to know of their
existence. It not only makes mote .complete
the list of the miner.als that occqr in th~
Witwatersrand' mines, but it might lead to
other disclosures such 'as evidence affecting
the origin of. the gold, etc., in the banket.
.
The first mineral gersdorffite is essentially
"a sulpharsenide of nickel (Ni.As.S) but it
is known that iron an~ cobalt sometimes
. replace som,e of. the ~ckel. .Ii). a paper
~944
.pre·sented to this Society in October,. 1923,
,entitled ".Mineral Constituents .. of Eand
Concentrates,". Mr. R. A. Cooper _referred
to
a
nickel
cobalt iron arsenide
(Nl. Co Fe) As. associat~d withjron pyritis.
and gelena,which. occurs in .appreciable.
quantity at Modder East. The amalgama- .
tion barrel residues at Modder East which
are returned to the reduction circuit
contains 0'33 percent. nickel, 0·11 per
cent, cobalt, and 0·80, per ·cent. arsenic,
and it is believed that the presence of this
nicke} arsenide adversely affects gold
extraction by cyanidation.
. When presenting ,the paper to which I
have referred, Mr. Cooper displayed' a
specimen of millerite taken from a cavity
in the reef in the Far East ·Rand.
'
.
.
Pyrrhotite occurs in considerable quantity
.on some. Witwatersrand mines and, its
presence demands thorough oxygenation of
the ore prior to cyanidation, otherwise
gold extraction is adversely affected.
.
Again I wish to eXpress', on your. behalf,
our indebtedness to Mr. Mendelssohn for
his valuable contribution, and I now
formally move a hearty vote of thanks to
him.
Dr. R. A. Pelletier intended to take part·
in the discussion personally, but, unfortunately, he cannot be .here in .person
this evening. However, Mr. M. Falcon has
kindly consented to read Dr. Pelletier's
contribution.
.
'Dr'- R. A. Pelletier (Member): Mr'-President, gentlemen, geologists and miping men
on the Ranq are apt to take for granted that
there is nothing more· to learri <about the
minerals of the banket; or those associated
with it, .and this attitude has led to indifference which is all the more 'regrettable
as a really exhaustive investigation of the
sulphide minerals of the banket with.'
modern methods of research now at our
disposal' has 'not' yet been made.
Mr.
Mendelssohn's contribution to-night is' !lcase in point when two new minerals,
gersdorffite and cubanite have been
recorde,~ ,for the '. first, time. as occurring
in vugs and druses mostly within quartz
veins in close proximity to banket beds.
The occurrence of the troilite, a' member of
the pyrrhotite group,
of consi.derable
is
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Nov ..Dec"
Jour.~a! of ~he Chemical,Metallurgical anq, Mining Society oj Sput.h Africa.
E. Mendelssohn-Notes' on Some ,Sulphide Minerals from the Far East Rand. ,
1944]
scientific. importance, as it .is a ra~ity in
terrestial deposits.
'
,Weare indebted to Mr. Mendelssohn
for having given us', an a,uthoritative and
,'detailed description of these minerals and
their mode of occurrence. We are equally
il).debted to Mr. Flugge-de Smidt, whose
interest and well-known enthusiasm in the
matter is mostly responsible for 'their.
discovery .• Through his o~n proficiency as
a mineralogist, which is considerable, and
by encouraging miners to, bring him o any
unusual minerals they may find he has
created a real interest in'the subject in the'
'mines with which he is ,in contact and which
has been most fruit~ul in results.I hope' these discove~ies,' will further'
promot,e interest in these matters;· there
is no doubt in my mind that there 'are
other r~rer minerals which have not yet
been recognised in our mines, and in the
Banket itself there, still remains splendid
opportunities for detailed studies of the.
opaque minerals' by means of the ore micro·scope.
' ' ,
0
\
The President: Perhaps' Dr. ,Zer,matten would like t«;, speak 1
Dr. H. L. J. Zermatten (Member): Mr.
President and gentlemen" I am sorry that
I have not been' able to 'prepare a contribution to the discussion in full detail" but,
I thank you. f<?r:. giving me ,tb~ <?pportunity of saying a few words concerningthe research work I have d6n'ein 'regard to
sulphide mInerals.,
',.. "
I am very interested in, the genetic origin
of those, minerals associated with gold in
the reef.'
" ,'. ' ,
, ' ' :'
I maintain 'that' still 'm6~e' different
minerals, formed in the reef, ,will, in the
future, be found and described, and that we
shall be able ,to expect, later. on, a better
'way of explaining wliy it is that the gold in
the reef is found in. the places it is. ' . ,
All .those crystals that are describt)d
by Mr. Mendelssohn are 'actually formed
t.hrough
physico-chemical
reactions
dependent on pressure and temperature.
Why should .the' equivalent' rsulphide
minerals, without crystal forms, found. in
the reef 'also not' be dependent on the
same pressure and temperature 1 . Gold -is
found nowadays in certain chutes.. Why
89
,is it that the gold in these chutes should
not be ,dependent purely ,on the physica,l
, and chemical features ?
I
have pleasure in thanking. Mr.
Mendelssohn for his excellent description
of these unusual sulphide minerals, and I
hope, at a future date, to present a paper
which will
with all these points.,
- deal
.
The President:' We thank you, Dr
Zermatten.
We, will keep you to your
promise. Now may I ask MJ::. Flugge-deSmidt· to 'contribute to the 'discussion'?
Mr. 'R. A. H. Flugge-de. Smidt
(Member), Mr.' President and gep.tlemcn,
beyond -encouraging underground officials
such as shift bosses, surveyors, samplers
and, those attached to the study department to bring
anything in thc way .of
minerals that they may consider interesting,
I cannot claim to have discovered any of
the minerals described by Mr. Mendelssohn.
Millerite ,was located by a miner who
, thoug~t', he haddiscQvered some visible
'gold 'and, subsequ'ently .. more was found
in the 'shale footwall of his stope.
" ,On showing, specimen' to Dr. N. Schindler
of 'our Mines Geological Department, he
immediately suggestl'Jd millerite.
. Cubanite :w~s discovered in situ by Mr.
L. de Waal who' was 'at that· time attached
tot.he, Sampling ,Department. I showed
specimen~ tq .Dr.' Zermatten, the geologist
at' that time' on New State Areas, who
-- considered the mineral to be cubanite.
, Gersdorffite iIi crystal form was found by
a G,M.T;S. instructor, Mr. L. Blignaut.
·It occurred,.in a' thick layer of quartz
'between the .reef and the shale contact.
When freshly expcsed, the' crystals showed
a/ bright silver lustre, but became tarnisl\ed
after a few days.'
,
Pyrrhotite, ,which is sometimes found in
huge masst)s, should be interesting t<?
mining men as a possible source of H 2S.
There are, uhdoubtedly, different forms of
pyrrhotite, as il). some cases specimens
. show no apparent 9hange over a period 01
years, whereas in C!ther cases it decomposes
rapidly.
Another mineral :that might be added to
this list of discoveries is barytes. Although,
I understand, BaSO 4 has been detected
me
a
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90
. Journalotthe Chemical, MetallJlrgical and' Mining Society of South Africa.
[Nov.·Dec., 1944
F.- J. Tromp and J. J. Matthee-Activated Carbon for Reg,enerating Used Fabricating Oil.
in a micro.sco.pic slide, this is the first
mentio.n o.f barytes being fo.und in a hand
specimen. Po.rtio.ns o.f a crystal o.f baryte!? .
were fo.und by ano.ther G.M.T.S. instructo.r
Mr. P. G. Ro.o.s, in a sto.pe in East Geduld. '
So.me time later; Dr. Zermatten fo.und a
-well-fo.rmed crystal' o.f barytes which is.
amo.ng the exhibits here to.-night.
-Quite ~ecently, so.me needle-shaped
crystals o.f a pyritic mineral were - fo.und
by a G.M.T.S. apprentice in a sto.pe o.n
East Geduld.
This' mineral" is lighter in co.lo.ur than.
,cubanite apd do.es no.t 'sho.w .striatio.ns
either o.n the prisms o.r. tabular forms
whereas the cubanite fo.und o.n East Geduld
is heavily striated.. Again this mineral
sho.ws many T. and L.-shaped fo.rms,
whereas aggregates o.f cubanite crystals
are o.ften shaped like arro.wheads. This'
may merely pro.ve to. be an unusual fo.rm o.f .
so.me well-kno.wn mineral, but in any case
it awaits determinatio.n.
•
Dr. Zermatten at o.ne time co.nsidered
East Geduldto. be a sto.reho.use' o.f· rar~ .
minerals, but that is no.t the case. :Mr.
Mendelsso.hn,
after
having' identifi~d
cubanite, fo.und this mineral in specimens o.f
reef in the mineral co.llectio.n
University. Dr. Pelletier, fo.und
o.n so.me calcite .crystals fro.m the
and Jack, while Dr.' Zermatten
fo.und much cubanite as well as
o.f the
millerite
Simmer
' himself
barytes.
The President: Gentlem'en, if' there
are no. further co.ntributio.ns to. the dis-.
cussio.n o.n this paper; may I dirf:)ct yo.ur.
. attentio.n to. o.ther papers that q,re o.pen to.
discussio.n.
If there is no.thing further fo.rthcoming, I
wan't to. tell yo.u abo.ut the. next meeting.
The next meeting will be held. o.n the 28th
February. Our S0.9iety will be, in recess
during December an~ January.
That" co.nclud~s th~, agenda' fo.r this
evening.
As this Will be o.ur last meeting befo.re the
end o.f the year, I wo.uld like to. extend to.
yo.u all hearty Christmas greetings and best
wishesfo.r a pro.spero.us.and victo.rio.us New
Year.
I thank the vario.us autho.rs fo.r their
co.ntributiQns, and I also., thank yo.u all fo.r
yo.ur attendance. I no.w declare the meeting
clo.sed (IO'p.m.).
ACTIVATED CARBON FOR REGENERATING USED LUBRICATING OIL.
By DR. F. J. TRC?MP (Member) and J. J. MATTHEE (Visito.r).
(Fuel Research
Insti~ute
G. Armstro.ngSmith (1) has sho.wn that
magnesia, prJduced by he~ting magnesite
to. co.mparatively lo.w temperatures, has the
pro.perty .o.f deco.lourising l!sed lubricating
o.ils and o.f remo.ving fro.m such o.ils acidic
and o.ther harmful impurities. The deco.lo.1!risiilg po.wer o.f this material was po.o.r,
ho.wever, and it also. gave rise to. filtratio.n
difficulties. On keeping it. in bags it rapidly
hydrated and·lo.st much·o.fits activity. The
activity o.f naturally o.ccurring·earths, fo.und
in the Unio.n up to. the'present time, is also.
,generally po.o.r.
Smith was therefo.re
'requested to. make an 'activ~ carbo.n fro.m
wo.o.d and co.al. He sho.wed that wattle
charco.al and lo.w temperature coke co.uld be
suitably activated by steam at abo.ut
1,000°C. The lo.ss o.f carbo.n amo.unted
of South Africa). .
to. 40-50 per cent. The plant was so.mewhat
and it was very do.ubtful whether
such plant co.uld be o.bt!!tined·in the Unio.n
during. the war. The co.mplicatio.n o.f the
'plant aro.se. fro.m the necessity o.f transmitting heat ·to. the charco.al o.r co.ke thro.ugh
so.me co.ntaining wall. Attempts were made
.to. avo.id this by intro.ducing. direct heating
in the fo.rm o.f inco.mpletely co.mbusted
pro.ducer gas" derived' fro..m charco.al. In,
this case activatio.n wo.uld be due to. bo.th
steam and carbo.n dio.xide. Ho.wever, the
carbo.n thus pro.duced was fo.und to .be o.f
po.o.r activity.
Smith then inves~igated
metho.ds o.f pro.ducing active carbo.n by
impregnating wo.o.d with so.lutio.ns o.f zinc
chlo.ride, pho.spho.ric acid, etc., then car~labo.rate