162 Chronicles of Science. j Jan. 
powers of the pure metals given in the following table, shows the places 
which the above metals take in the series. 
Conducting Power at 0°. 
Silver . hic : : ; : - 10000 
Coy o so a oS eS lg) BBE 
Gold 5 6 A 5 + : ; 5 77-96 
Zine 5 6 - é ' 5 c $ 29°02 
Cadmium . 5 3 c é . 4. YBYTD. 
Cobalt . O 5 : ° : S 4 Wy (Pe 
Tron : A : 4 ‘ a 5 16°81 
Nickel . Aohpees 5 F ‘ ‘ 5) PLL 
Tin ; ; ; ‘ ; ; ; 5 12°36 
Thallium ° Bee me Path othr F A 9°16 
Lead . 6 A ‘ é - ‘ ‘ 832 
Arsenic . C A : : . c ; 4-76 
Amik? 96° “5 9 6 oo G Oo 4°62 
Bismuth 4 See ame ‘ 4 1-245. 
It has long been a desideratum amongst electricians to obtain a 
battery having the constancy of Daniell’s without the annoyance 
attending the use of a porous cell. Two such batteries have been 
described lately. One is the invention of M. Jacobini, and consists of 
a glass vessel, in which is placed a cylinder of copper pierced with 
holes ; outside this is a larger cylinder of zinc. The copper cylinder 
is filled with powdered sulphate of copper, tightly pressed down, and 
the remainder of the space in the glass vessel is filled with sand, 
touching the zine cylinder on both sides. Water is then poured in, so 
as to saturate both the sand and powdered sulphate of copper, and the 
arrangement is covered up. Several hours elapse before the electric 
current begins to develope itself actively. It then increases for a few 
days, and finally sinks again till its power becomes constant. Father 
Secchi has had a battery of this kind in use for three months, and 
reports that it is as efficient as when first constructed. 
The other battery is the invention of M. Grenet, and is a modi- 
fication of the sulphate-of-mercury pile of M. Marie-Davy. At the 
bottom of a glass jar a quantity of acid sulphate of mercury is placed. 
A stick of gas-carbon and a cylinder of zine are supported upright in 
the jar by means of a cork, which closes the upper part of the vessel ; 
water is then carefully poured in, and the whole is set aside, where it 
will not be shaken or moved. A wire connected with the carbon forms 
the positive pole, whilst the zinc forms the negative pole. The water 
becoming gradually charged with sulphate of mercury, attacks the zine ; 
the hydrogen which is evolved reduces the mercury on the carbon, and 
the metal as it accumulates falls down to the bottom of the vessel. It 
the apparatus is not shaken, there are formed two layers of Lquid— 
the lower one consisting almost entirely of a solution of the mereury 
salt, whilst the upper layer contains the sulphate of zinc. It is owing 
to this separation that the porous vessel is able to be dispensed with. 
The battery is employed of two sizes—the larger one contains 500 
grammes of water and 100 grammes of mercury salt; the smaller con- 
tains respectively 100 grammes and 380 grammes. They are said to 
keep in perfect order for six months at a time, without once requiring 
to be touched. 
