654 EXPERIMENTAL INVESTIGATION OF THE 
subject. But I am in hopes of obtaining unequi- 
vocal results before the second part of this 
memoir is brought before the Society. 
38. With respect to brass, one of our most im- 
portant alloys, I have found it to be highly mag- 
netic in a great number of cases ; viz., in all the 
various states of newly cast brass, brass wire, 
and sheet brass; as well as in several articles of 
brass manufacture. But, from the very great 
difference in the degrees of magnetic action dis- 
played by different specimens of this beautiful 
alloy, and the total absence of that action in others, 
there has appeared to me a high degree of proba- 
bility that the magnetism displayed by brass is 
due to accidental portions of iron in the alloy. 
39. Cavallo discovered that in magnetic brass 
the action was more powerful in large pieces than 
in small ones. This fact 1 have also observed in 
several specimens that I have examined. The 
reason seems to be that in the larger pieces a 
greater quantity of ferruginous matter (if pre- 
sent), is brought into operation than in the small 
pieces. 
40. Cavallo also states, that hammering an un- 
a 
