Magneiism, Cohesion, Adhesion and Viscosity. 'tSS 



being only raised by the same process to 85^. I attribute this 

 peciib'arity to the greater number of points that are brought 

 in contact with the magnet where the surface is flat. The 

 character of the magnetism thus acquired is entirely the same 

 as that of steel, attracting and repelling in the same manner, 

 but comparatively in a very low degree, and consequently 

 quite superficial. If brought quite close to that end of the 

 needle for which it exhibits repulsion, it will, like a magnet, 

 in consequence of the proximity, attract it. It lost its mag- 

 netic power in the course of a few weeks, but it has since 

 been renewed with the same facility as before. 



It appeared to me that the needles got out of order, for a 

 short space of time, by their contact with the iodine and 

 arsenic; but upon this point I cannot at the present moment 

 speak positively. Certain it is that ihey became quite para- 

 lysed on two or three occasions, but were restored by having 

 recourse to the touch, and subsequently by only letting them 

 lie quiet an hour or two. 1 suspected the same effect to have 

 taken place once or twice, after keeping them in contact with 

 antimony, but at other times I could assign no cause for the 

 change. 



All the specimens of brass I have examined are very mag- 

 netic, and may have that property considerably increased by 

 putting them in contact with a magnet. One specimen, 

 which is a bar, causes attraction at one end, but the repulsion 

 which existed at the other has disappeared. The former 

 state appears to continue unchanged, at least I have seen no 

 difference in the course of a year. Bell-metal has very low 

 magnetic powers; so much so indeed that I despaired of 

 making the needle connect itself with it; nor was this object 

 effected till they had both been kept in connexion for some 

 lime, and even then there was every symptom that this was 

 attained only by overcoming a natural repulsion, as in the 

 case of chromium, of which I have already spoken. No 

 change seemed to be effected by keeping it in contact with a 

 magnet. German silver is magnetic, and if brought within 

 about the eighth of an inch of the needle will attract it. But 

 the specimen I had, seemed by its colour to contain an unusual 

 proportion of copper, or otherwise it might have proved more 

 magnetic. No increase of magnetism resulted from connec- 

 tion with a larger magnet. Cobalt and manganese, as is 

 known, attract. The needle clung at once to a globule of 

 mercury, against which it had been urged by the magnet. 



All the rarer substances, including pure gold, in the pre- 

 ceding class, I believe to be chemically pure, as they were 

 obtained from Messrs. Boyveau and Pelletier, and M. Ber- 



