On Electricity by Position or Induction. 915 
port wine be added to 22 parts of alcohol and 88 of water 
(in a state of perfect combination), the mixture is precisely 
analogous in its intoxicating effects to port wine of an 
equal ‘strength, 
In the table annexed to my former paper, it appears that 
the average quantity of alcohol contained in port wine 
amounts to 23,48 per cent.; but two of the wines there 
alluded to are stronger than any T have since met with, and 
were at that time sent to meas “ remarkably strong and old 
port.”” I have lately examined a number of specimens of 
the better kinds of port wine in common use, and the re- 
sults of these experiments lead me to place the average 
Strength of 22 per cent..of alcohol by measure. 
A ‘port wine procured for me by Dr. Baillie, and to which 
no brandy had been added, afforded 21,40 per cent. of al- 
cohol: another specimen of a similar description, put into 
my hands by an Oporto merchant, contained only 19 per 
eent.; it is the weakest port wine [ have met with. 
The other results given in the table agree perfectly with 
those of Pre and more extended experiments. 
XXXVIIL On Electricity by Position or Induction. By 
Ez. WaAcKeER, Esq. 
To Mr. Tiiloch. 
Dear Sir,—Ln my paper on Mr. Bennet’s Electrometer, 
[ asserted that electricity by position or induction * does 
not vanish as soon as the electric is removed, though Pro- 
fessor Robison and other writers on electricity are of a 
contrary opinion. 
The Professor observes, that ** the mechanical phzno- 
mena of electricity may be expressed in a few simple pro- 
posiuions. ‘The most general fact that we know, and from 
which all the rest may be deduced, is the following. 
«* If any body A is electrified by any means whatever, 
and if another body B” (supported by an insulating stand) 
** is brought into its neighbourhood, the last becomes élec- 
trified by position. 
“© The mere vicinity of the electric renders the conductor 
electric, and the electricity ceases on removing the excited 
surface >.” 
* “Tt wil) be convenient,” says Dr. Robison, “to distinguish this last elec- 
trical state by a particuiar name. We will call it Electricity Ly position, or 
Jnduced Electricity. Mt is induced by position with regard to the perma- 
ently electrical body.’ —Encyel. Sup. vol. i, p. 568. 
+ Encycl. Brit. Sup. vol. i. p. 571. 
O4 But 
