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The filtrate from Group I. may contain all other basic

Pb, Hg, Bi, Cu, Cd, Pd, Sn, Sb, As, It must be freed from HNO,: this may be done by evaporating with slight To the HCl solution, which should be concentrated if it has been rendered too agitated, and allowed to rest for some hours.

A yellow crystalline The filtrate should be mixed with a reasonable quantity of precipitate of KPCL, indicates Pt. 1 A precipitate con- !

con- | Through the filtrate a current of

Through the filtr The largest part of the sisting of yellow l sonnnd and even a third stream of rare metals R, Ru, Ir,

F, 1 spangles, or of a and also some Paci,

thoroughly washed with hot water I would separate here in brown yellow sponge, c.

onge, S; the undissolved portion must be the same form. I indicates Au.

The residue may contain Hg, S, Pb.,S, Bi,S, Cu,S, Cd, S, and Pd, S: it must be washed until quite free from Cl, then boiled in concentrated HNO, until all red fumes cease. The liquor is diluted with H,O, the residue allowed to settle, and dilute H,SO, added until precipitation is complete; it is then agitated and filtered.

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The residue and precipitate. The filtrate may contain Bi, Cu, Cd, and Pd. may contain

Add some quantity of solution of KCl; evaporate Hg, S and Pb. So, to dryness on a water-bath, adding a little niDivide it into two portions. trohydrochloric acid towards the end of the

operation. Redissolve in a solution of KCI,

adding one drop of HCl; filter and wash with Boil in HCl; Ignite on a KCI. add one or fragment two drops of of porcelain. A reddish To the filtrate add excess of NH HO. HNO3, and / A white yellow continue to non-volatile crystalline A white | The filtrate may conboil. Drop residue of precipitate precipitate tain Cu and Cd. Aciin a bright Pb, son of KPC1, of BiH,O, dify with HCI, and fragment of indicates | indicateso | indicates saturate with H.S; filcopper foil. Pb.

Pd. Bi. ter and wash the preA silvery film

Confirm by cipitate with H,Oʻimon the foil

the oxychlo- pregnated with H,S. indicates

ride test | Boil the precipitate |(see p. 182). with dilute H, SO2, and

filter quickly.

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To the so- The prelution add cipitate is excess of Cu,s.

H.S. A Dissolve, yellow pre- and confirm

cipitate by the indicates | NÉHO Cd. and X, Cfy

tests for


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* The separation of these four metals is most difficult : the process will be described in an Appendix to the present Table.

+ This process was, we believe, originated by Dr. Hofmann, and is employed by him in the Royal College of Chemistry.

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The precipitate may contain
Mn, Fe, Co, Ni, u, Ti, Zr, Ce, La, Di, Y, and th, together with the phosphates,

borates, and fluorides.
First dissolve in HCl, avoiding excess, and boil the solution for some time ; filter.

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A white pre- To the filtrate, some quantity of a saturated solution of K2904 is added, the cipitate of liquid allowed to rest for some hours, filtered, and the precipitate washed with

cold saturated solution of K2SO4. indicates the presence of

The solution is boiled with a few drops Ti. The formation of a white,

of HNO,, slight excess of NH HO added, yellow, o od crystalline precipitate of double sul- and then a warm and concentrated solution phate would indicate the of (NH),CO2, with which the precipitate presence of

formed is digested at a moderate heat for Zr, Ce, La, Di, and Th. some time. It is then filtered rapidly while

As all these rare bodies | hot, and the digestion with (NH.),CO,
are never known to occur

together, their separation
is not a matter of prac-

The preci- The filtrate will contain the
tical importance.
pitate will

U, Ni, and Co,

contain the also the phosphates, borates, and fluorides.

and, if concentrated, will, on drops of HCl, and drop into boiling KHO

cooling, deposit fine lemonmixed with a little Na, Cog.

yellow crystals of

(U,O) CO, (NH4)2CO3, The solution should be examined for phos- which may be separated. Add phoric, boracic, and hydrofluoric acids, by some NH Cl solution, and boil the appropriate tests.

for some time.

The precipitate will consist of (U20)20. Test by means of the blowpipe for U.

To the filtrate add

Na, Co,, and boil until all odour of NH, has ceased, then almost neutralize the Na, Co, with HCl. Add now, gradually, such a quantity of a weak solution of KČy as shall be exactly sufficient to redissolve the precipitate at first produced by it. Boil until HCy ceases to be evolved ; filter, if necessary, and, when cold, add some excess of a strong solution of NaClO*. If no black precipitate or colour appears after the lapse of ten minutes, add a drop of HCI to facilitate its formation. Warm and filter.

The precipitate will consist of (Ni,),0,. The filtrate will contain the Co. EvaTest by means of the blowpipe for "porate to dryness, and test by means Ni.

of the blowpipe for


* This mode of separation was, we believe, first practised by Dr. Hofmann.


The filtrate from the (NH), S precipitate freed from (NH), S by boiling and filtration, having been mixed with (NH), CO, and warmed in the presence of NH, CI, may have yielded a precipitate consisting of the carbonates of Ba, Sr, and Ca.

The precipitate is dissolved in a few drops of HCl and divided into two portions.

II. is mixed with some quantity of is mixed with some quantity of soH, Si, F., and evaporated to dryness. lution of K, SO,, evaporated to dryThe mass is then treated with EHO. ness, and the mass boiled with water

and filtered.


A residue | The filtrate is again consists of mixed with H, Si, F., The residue To the filtrate, excess

Ba, Si, F., and again evaporated consists of of NH, HO is added, and indicates to dryness to ensure Ba, SO, and and a few drops of

the complete separa- | $r, so, (NH,),Ō, when a tion of Ba. The so

white precipitate lution in EHO is re

peated, the liquid eva-

porated to dryness,
and the residue dis-
solved in water and
tested with solution
of Ca, SO,, when a
white precipitate in-



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The filtrate from Group IV., or the solution in which the various groupreagents have failed to produce any precipitate, may contain NH,, Mg, Ř, and Na. Evaporate and ignite to expel NH, salts, which will have been already detected in the preliminary examination; mix the residue with mercuric oxide (Hg, 0) in excess, and a drop of water; ignite, extract with boiling water, and filter whilst hot. A residue will con- Evaporate the filtrate to dryness, test one porsist of MgHO, and in- tion of the residue before the blowpipe for dicates the presence of


dissolve the remainder in dilute HCI, and add
HPtClz. A yellow crystalline precipitate of KPCI,



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