HILLEBEAND.] ALKALIES. 99 
with absolute alcohol 1 or with that of 80 per cent strength, filtered 
by decantation through a wit small filter and washed by decantation 
with alcohol of the same strength. The precipitate is tiol brought 
onto the filter more 1 than can be avoided. Dish and filter are then dried 
for a few minutes to remove adhering alcohol, the content- of (he 
former are transferred to a weighed platinum crucible or very small 
dish, and what still adheres to the porcelain is washed through the 
filter with hot water into the weighed receptacle. This is now placed 
on the water bath and afterwards heated to 135 C. in an air bath. 
The factor used for reduction of K 2 PtCl 6 to 2 KC1 is 0.307 and of 
2 KC1 to K 2 0, 0.632. 
LITHIUM. 
After separation of the potassium platinic chloride, the alcoholic 
nitrate is evaporated and tested spectroscopically for lithium. This 
(dement is almost invariably present, but almost never in amount to 
warrant quantitative estimation. Should it be so, however, the very 
excellent Gooch method (summarized below) of separation by amy] 
alchohol is to be followed, after removal of the platinum by hydrogen 
gas. 3 In rock analysis there need be no fear of enough lithium falling 
with the potassium to cause any concern. 
If ammonium carbonate alone has been relied on to separate all cal 
cium (ante, p. 98) the few tenths of a milligram of calcium chloride 
that escaped precipitation can now be found with the sodium. 
gooch's method 3 for separating lithium. 
To the concentrated solution of the chlorides amyl alcohol in added and heat is 
applied, gently at first, to avoid danger of bumping, until, tin; water disappearing 
from solution and the point of ebullition rising and becoming constant for some min- 
utes at a temperature which is approximately that at which the alcohol boils by 
itself, the chlorides of sodium and potassium are deposited and lithium chloride! is 
dehydrated and taken into solution. At this stage in the operation the liquid is 
cooled and a drop or two of strong hydrochloric acid added to reconvert traces of 
lithium hydrate in the deposit, and the boiling continued until the alcohol isagain free 
from water. If the amount of lithium chloride present is small, it will now he found in 
solution and the chlorides of sodium and potassium will be in the residue, excepting 
the traces for which correction will be made subsequently. If, however, the weight 
of lithium chloride present exceeds 10 or 20 milligrams, it is advisable at I his point, 
jpreeht (Zeitschr. fur anal. Chcmic, Vol. XVIII, p. 513, 1879) claims that this is to be preferred to 
80 percent alcohol, especially if evaporation has been carried to dehydration of the sodium salt. 
Atterberg disputes this final statement and says that 80 per cent, alcohol gives better results. 
2 When haste is not an object, this way of Bunsen's for removing platinum from (he chlorid 
the alkalies is by far the neatest and most satisfactory. The small Bast containing the solution is 
placed ina water hath and attached to a hydrogen generator. After expelling all air the fit 
closed, wit iiout breaking connection with the generator, and left to itself , except for occasional lighl 
shaking up, till reduction is accomplished. \ more expeditious and very satisfactory reduction i> 
effected bj evaporating the solution to drj ness \\ Ith metallic m< rcury, then heating to expulsion of 
the excess of mercury and of its chloride (Sonstadt, .lour. Chem. Soc, LXVII, p 984, L895), w ho thus 
reduces potassium-platinic chloride in order to weigh its platinum. 
3Proc. Am. Acad ArtsSci., i>. 177, ism;, null. Q. S. Geol. Survey No. 12, p. 73, 1887; Chemical News, 
Vol. LV, pp. IS, 29, 40, 56, 78, L887; Am. Chem. .lour., Vol. IX. \<. 33 
