British Association for the Adva?icement of Science. 309 



magnetism, though its sum was nearly equal with the same coil, 

 was smaller when diffused through the particles of the larger mag- 

 net, and was unahle to disturb the magnetic equilibrium of the steel 

 needle. 



The Battery. The magnet designated above as No. 2. was tried 

 with a battery : 



lb. oz. 



No. 1. Double cell, each 1 foot square ; power 11 11 



2. 1 foot by 6 inches 6 11 



3. Single cell, 3 inches by 2-j- 8 



4. 1 inch square 2 



Same magnet with single cell of battery No. 2, and charged with 

 No. 1. 1 part sulphuric acid, 50 parts water; power. ... 5 

 2. 1 nitric acid, 50 .... 3 8 



The spark with these charges was at first very brilliant, but the 

 effect was transitory. 



No. 3. Diluted alcohol, 10 parts in 100 ; power 4 



4. 2 parts sulph. acid, 1 nitric acid, 100 water .... 11 10 



5. 1 part 2 100 .... 4 



No. 4. was tried with a helix interposed between the po- 

 sitive pole of the battery and the magnet. The lifting 



power was 1 



Another magnet being interposed, power 3 



When No. 4 was exhausted, so that it would lift only 1 

 pound, its zinc plate was raised out of the fluid and re- 

 placed ; this increased the power to 2 8 



When No. 4 would lift only 1 pound its fluid was poured 



into its other cell, and the power became 5 9 



8 pairs of plates in Cruikshank's battery caused magnet 



No. 4 to lift 5 8 



A calorimotor of equal surface, charged with a similar fluid 11 10 



Perhaps the increased tension of the electricity might be found of 

 advantage when the helix is of great length. 



In speaking of the charge, the author remarks that he is fully 

 persuaded of the necessity of decomposition for the production of 

 galvanic effect. A deflexion of 15° and more has been produced 

 in a galvanometer of great delicacy, which he constructed by merely 

 uniting, by a single corner of each, two tarnished pieces of metal, the 

 one zinc, the other copper ; the imperceptible perspiration of the hand 

 may have acted as a fluid, and some foreign substance deposited on 

 either or both metals have aided the decomposition. 



The Helix. Four magnets with different helices were used with 

 the same battery. 



Magnet No. 1. 8 inches long, -§- diam., coil 7-j- yards, power 11 



2. 4 6 



3. That with knobs already mentioned, coiled 



with 7-$- yards of wire 2 5 



Coiled with ribbon of copper on the knobs . . 2 



