TRANSACTIONS OF THE SECTIONS. 



27 



lbs. oz. 

 Magnet, No. I lifted in contact 25 3^ 



2 8 ll| 



3 39 3^ 



^ 4 39 3 



Fourth Series. 



To test the comparative excellence of different charges, the gal- 

 vanometer used on this occasion, was M, a small but good mag- 

 net; N, a 



needle, at zero, vphere the magnet was connected with battery B, 

 two inches square. 



The first deflection was carefully noted ; the number of degrees 

 at which the needle settled dovra, and the deflection after every 

 quarter of an hour for six quarters. 



Rain water was used; sulphuric acid, specific gravity 1840; 

 nit., spec. grav. 1410; muriatic, spec. grav. 1175; solution of 

 caustic potash, saturated. 



Rain-water and nitric acid 1 in 21 parts 



31 

 41 

 51 



Rain-water and sulphuric acid, 1 in 21 

 31 

 41 

 51 



Rain-water and muriat., 1 in 41 



. lin 51 



Solution caustic potash 



Sulp. 1 in 414, nit 1 in 83 



1 in 26^, — 1 in 53 



1 in 161f, — 1 in 323 



1 in 201^,— 1 in 403 



Muriat. 1 in 52 ; sulp 1 in 52 



1 in 52 ; nit 1 in 52 



1 in 52^; sulp 1 in 103 



Solution caustic potash and sulp. 1 in 51 



and nit. 1 in 51 



and mur. 1 in 51 



Sea water from Dublin bay 



and sulp. 1 in 51 



and nit. 1 in 51 



Sulp., nit., and muriat., each 1 in 53 



