256 
PROFESSOR TYNDALL’S FURTHER RESEARCHES 
Thus far then the following substances have been submitted to examination : — 
Diamagnetic bodies. 
Bismuth. 
Antimony. 
Heavy glass. 
Calcareous spar. 
Statuary marble. 
Phosphorus. 
Sulphur. 
Nitre. 
Wax. 
Magnetic bodies. 
Penrhyn slate. 
Caermarthen slate. 
Slate perpendicular to cleavage. 
Chloride of iron. 
Sulphate of iron. 
Carbonate of iron. 
Ferrocyanide of potassium. 
Oxide of iron, 
Iron filings. 
Liquids. 
Distilled water. 
Bisulphide of carbon. 
Liquids. 
Sulphate of iron. 
Muriate of nickel. 
Muriate of cobalt. 
Every substance in each of these lists has been proved to be polar under magnetic 
influence, the polarity of the diamagnetic bodies being invariably opposed to that of 
the magnetic ones. 
In his investigation on the supposed polarity of diamagnetic bodies, Mr. Faraday 
made use of a core of sixpenny pieces, and obtained with it the results he sought. 
Wishing to add the testimony of silver as a good conductor to that of copper, two 
cylinders were formed of sixpenny pieces, covered with paper and submitted to 
experiment. The following are the results obtained : — 
XXVIII. 
Silver cylinders (sixpenny pieces). 
Current direct. 
Position 1. 724 
Position 2. 774 
Position 3, 804 
The action here was prompt and energetic, strongly contrasted with the neutrality 
of copper ; but the deflection was permanent, and could not therefore be the result 
of induced currents. Further, it was a deflection which shows magnetic polarity, 
whereas pure silver is feebly diamagnetic. The cylinders were removed and examined 
between the poles of an electro-magnet ; they proved to be magnetic. 
On observing this deportment of the silver, I tried the copper cylinders once more. 
The results with a direct current were, — 
XXIX. 
Position 1. 766 
Position 2. 767 
Position 3. 768 
Here almost the same neutrality as before is evidenced. 
