80 Intelligence and Miscellaneous Articles. 
described by them* as accompanying the brilliant red line Lia, re- 
quires any extraordinary precautions to render it visible. Two 
specimens of lithium salts which I have examined in a very perfect 
apparatus, somewhat similar to the one described by them+, have 
failed to give the slightest evidence of its presence, although I have 
repeatedly examined them with that object; and as I know that 
other experimentalists in this country have been equally unsuccess- 
ful, it is possible that the presence of this line in the spectrum given 
by MM. Kirchhoff and Bunsen’s specimens of lithia may really be 
due to the presence of another element hitherto unknown. The 
spectrum of the new alkali metal Cesium (which it may be of interest 
to know I have detected in some highly concentrated mother-liquors 
from sea-water) is in no respect similar to it. It will bea sufficient 
proof of the delicacy of my apparatus, to say that it is constructed 
principally of quartz, and that it easily separates the double line D. 
I remain, Gentlemen, 
Your obedient Servant, 
WiLuiAM CROOKES. 
A CONSTANT COPPER-CARBON BATTERY. BY JULIUS THOMSEN. 
In the ordinary galvanic apparatus, zinc usually officiates as posi- 
tiveelement. ‘This metal is, however, readily attacked by acid if it is 
not either chemically pure or well amalgamated. if the sulphuric 
acid is not greatly diluted, the zinc cylinders are strongly attacked 
by continuous use, in spite of the amalgamation, by which a great loss 
of metal is caused ; if, on the other hand, the acid is much diluted, it 
is soon saturated, and the action of the apparatus is enfeebled. 
In my investigations I use a galvanic apparatus consisting of cop- 
per in dilute sulphuric acid.(1 part acid and 4 parts of water) as positive 
element, and, as a negative element, carbon in the mixture of bichro- 
mate of potass, sulphuric acid, and water, recommended by Wohler 
and Buff. (Buff uses 100 parts water, 12 of bichromate, and 25 of 
sulphuric acid.) The electromotive force of this combination is ;%,ths 
of that of a Daniell’s battery. 
Its advantages are as follows :—The copper is not at all attacked 
by the acid when the circuit is open ; the resistance of the sulphuric 
acid, from its being so little diluted, is a minimum: the sulphuric acid 
is so strong that it can be used for months without becoming satu- 
rated. As, further, the mixture of chromate of potass and sulphuric 
acid is inodorous, this combination is very convenient for working 
with in closed spaces. 
This combination is very interesting theoretically ; for as copper 
cannot decompose dilute sulphuric acid, the copper-carbon element 
is an example of a powerful apparatus in which chemical action and 
the disengagement of electricity are quite inseparable.—Poggendorff’s 
Annalen, October 5, 1860. 
* Phil. Mag. S. 4. vol. xx. p. 96, August, 1860. 
t+ Ibid, p. 90. 
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