512 Sir G, C. Haiighton on the Connnon Nature of 



to deserve particular attention, and have been carefully tested. 

 Their strong attraction for non-ferruginous bodies must prove 

 interesting, and Iceland spar vies with them in that property, 

 for the needles had only generally to be pushed against it to 

 form the connexion. The porcelains exceed even the glasses 

 in their affinities for non-ferruginous bodies. The attraction 

 of glass for sugar candy, rock salt and alum, is worthy of at- 

 tention. The metals were not tried, for want of time, with 

 the exception of gold and tin. 



The case of carbonate of iron is very remarkable, for it 

 might a ]jriori be supposed that from the large proportion of 

 iron it contains, it would show considerable atti'action for the 

 magnetic needle > but this is so far from being the case, that 

 it will be seen to be one of the lowest in the scale, and after 

 being kept eighteen hours in contactwith the N.pole of a horse- 

 shoe magnet capable of raising thirty pounds, its affinity for the 

 magnetic needle was not increased. It might also have been 

 expected, from its great density, and the analogy of similar 

 cases, that in consequence of its feeble attraction for the mag- 

 net, it would exhibit a strong affinity for glass. It however 

 is otherwise ; and by a reference to all the metals with which 

 it was tested, in consequence of these peculiarities, it will be 

 seen to be one of the most remarkable and interesting sub- 

 stances that have been tried, exhibiting a very low state of 

 attraction for almost all bodies, gold, silver, cadmium, tin and 

 zinc being excepted, and for these metals it exhibits a re- 

 markable affinity. The results of many of the experiments 

 on various bodies will show a kind of elective affinity, as is 

 observed in chemical combinations ; and no substance exem- 

 plifies this remark so completely as carbonate of iron. Thus 

 though it has the strongest affinity for zinc, it does not show 

 an attraction for brass above what it exhibits for copper, 

 which is as low as H-". Yet most bodies have a surprising 

 affinity for brass. Carbonate of iron affiards a fresh instance 

 that the iron in a body may be quite inert, in consequence of 

 its combination with another substance neutralizing its affini- 

 ties. 



The low affinity of the magnetic needle for marbles is quite 

 in accordance with the experiments of Dr. Seebeck, and the 

 numbers he obtained for bismuth, platinum and antimony, 

 bear a singular resemblance to those afforded by the present 

 experiments. There may be the same accordance between 

 the others, but there is no means of marking by the present 

 mode, the nice shades of difference after 90°. Silver, which 

 he places next to iron in power, seems to take the place of 

 brass, which 1 find to be generally singularly magnetic. 



