1853.] OF THE ROYAL INSTITUTION. 233 
and filling it successively with various gases and fluids, including 
always air and water in each series, these included bodies may then 
have their results reduced and be entered upon the list. The 
following is a table of some substances estimated on the centigrade 
scale, and though there are many points both of theory and practice 
yet to be wrought out, as regards the use of the torsion balance 
described, so that the results can only be recorded as approxima- 
tions, yet even now the average of three or four careful experiments, 
gives an expression for any particular substance under the same 
conditions of distance, power, &c. near upon and often within a 
degree of the place assigned to it. The powers are expressed for a 
distance of 0.6 of an inch from the magnetic axis of the magnet as 
arranged and described, and, of course, for egual volumes of the 
bodies mentioned. The extreme decimal places must not be taken 
as indicating accuracy, except as regards the record of the experi- 
ments: they are the results of calculation. Hydrogen, nitrogen, and 
perhaps some other of the bodies near zero, may ultimately turn out 
to be as a vacuum; it is evident that a very little oxygen would 
produce a difference, such as that which appears in nitrogen gas. 
The first solution of copper mentioned was colourless, and the second 
the same solution oxidized by simple agitation in a bottle with 
air, the copper, ammonia, and water being in both the same. 
Prot-ammo. of copper 134°23 Camphor . = =, (200g 
Per-ammo. of copper 119.83 Camphine ‘ «,. 582.96 
Oxygen : 3 - 17.5 Linseed oil ; . 85.56 
ae 5 4 2) 3.4 , Olive.oil. . : Pirnbat =o H3) 
Olefiant gas 0.6 Wax ‘ c - 86.73 
Nitrogen 0.3 Nitric acid ¢ ee easel) 
Vacuum A 0.0... Water ov 96.6 
Carbonic acid gas 0.0 Solution of Ammonia. 98.5 
Hydrogen : 0.1 _Bisulphide of carbon 99.64 
Ammonia gas : - 0.5 Sat. sol. Nitre . - 100.08 
Cyanogen 0.9 Sulphuric acid . - 104.47 
A Glass . 18.2 Sulphur. ne ALS. 
Pure Zinc. - . 74.6 Chloride of Arsenic - 2S 
Ether . : . 75.3 Fused Borate lead . 186.6 
Alcohol absolute : . 78.7. Phosphorus . : 
Oilof Lemons. . 80. Bismuth . : . 1967.6 
Pliicker in his very valuable paper* has dealt with bodies which 
are amongst the highly paramagnetic substances, and his estimate of 
power is made for equal weights. 
One great object in the construction of an instrument delicate 
as that described, was the investigation of certain points in the 
philosophy of magnetism ; and amongst them especially that of the 
right application of the law of the inverse square of the distance 
as the universal law of magnetic action. Onainery magnetic 
* Taylor’ 8 ‘Getedtitic Memolrs, v. 713, 730. 
