NATURAL PHILOSOPHY. 117 



There are, however, other striking instances. Silver is a metal pos- 

 sessed of only feeble torsion balance magnetism ; in its dark-colored 

 sulphuret and oxide, the attraction is more decided ; the white chloride 

 is like the pure metal, very feeble in its attraction. Through the 

 influence of light it passes to the dark oxide, gaining magnetic force 

 with the change. Should these experiments be confirmed, this well- 

 known action of light on the chloride of silver will serve as a very 

 beautiful illustration, for in it the whole question is resolved; the light 

 effects a change in the color ; the alteration of color is accompanied 

 with an increase of magnetic attraction. 



Copper possesses a degree of magnetism so minute, that it is recog- 

 nized with the utmost difficulty on the torsion balance, yet it gives the 

 dark-colored oxide and sulphuret, both of which are strongly magnetic ; 

 for if well dried particles are spread upon a sheet of paper, some of 

 their particles are moved in the manner described. Palladium and 

 manganese exhibit somewhat similar properties. Arsenic, in its pure 

 state, is magnetic on the torsion balance, but when pulverized is not 

 disturbed by a magnet. In union with its equivalent of sulphur, the 

 ruby-red real gas is produced. Sulphur has been shown by Faraday to 

 be diamagnetic, yet in this union with arsenic a compound is given 

 that is far more magnetic than the metal, or any other of its products ; 

 for realgar when bruised and spread out upon paper can be moved 

 and can be streaked by the magnet. In most of the foregoing cases, 

 the dark magnetic substance is an oxide formed or set free by heating ; 

 but with this metal oxygen forms the well known white oxide, diamag- 

 netic according to Faraday, but which, with the feebler magnetic 

 force from a small steel magnet, proves slightly magnetic ; however this 

 may be, the contrast is striking between the feeble magnetism of the 

 white oxide and the decided magnetism of realgar. Carbon, in the 

 form of a pure diamond, is feebly attracted ; in the finely divided black 

 state the attraction increases, and in the coal left after the decom- 

 position of colorless starch, or sugar, there is a very great increase in 

 the magnetic attraction. In conclusion, Mr. Adie states, that ah 1 the 

 heavy metals, in every-day use in the arts, have furnished either 

 oxides, carburets, sulphurets, or fluorides, which contain particles suf- 

 ficiently magnetic to move on paper to an ordinary steel magnet passed 

 to and fro underneath. 



In the examination of the corollas of different flowers, it was found 

 that the white colors were, when fresh, diamagnetic, while the colored 

 corollas differed much, the diamagnetism of many being apparently 

 due to their moisture, which, at the same time, tends to make them 

 transparent. In dyed everlasting flowers, the various colors show very 

 well the change of magnetic properties, and, being in a dried state, the 

 results are not subject to that disturbance which the moisture of fresh 

 flowers occasions ; the pale-yellow is diamagnetic, the dyed chrome- 

 yellow nearly inert, the verdigris-green feebly magnetic, and the log- 

 wood-purple strongly magnetic. Solar rays bleach dead vegetable 

 matter with rapidity, while in living parts of plants their action is fre- 

 quently to strengthen the color ; two opposite effects, which, accor- 

 ding to my experiments, should be accompanied by different magnetic 



