12 t ANNUAL OF SCIENTIFIC DISCOVERY. 



material wis c msumed than when the battery poles are directly con- 

 nected with each other. Mr. Dickson's battery was described as one of 

 the hot class, the sulphuric acid was heated to 600 Fahrenheit. He 

 claims, by his mode of applying heat, to be able to use iron and other 

 cheap metals, instead of the dear ones, zinc, copper, &c. The relative 

 mobility of the atoms of an electrolite determined, he considered its force 

 r ither than its specific gravity . When oil of vitriol was heated to 350 Fahr. 

 only, the electric action is less powerful than when heated to 600 Fahr., 

 probably owing to the waves being less rapid. With the necessary per- 

 colating apparatus he was convinced that his battery would be successful 

 for lighthouse purposes. HH considered 15 of his cells equal to '20 or- 

 dinary cells ; three ofhis rolls are not equal to two of nitric acid cells, but 

 the increment in his battery w >.s greater. Grove's battery cost Is. od. 

 to produce the s'trrv. 1 amrmnt of electricity as that produced for 10 \d. 

 by j).c-;sn;i'>. Comparing the iiglitin-g powers, 11 ^d. with the caloric 

 birtery, will produce the same amount of light as Is. od- by Grove's. 

 He declared that the sulphur liberated at the negative poles could be 

 converted into sulphuric acid to the extent of ^. The oil of vitriol 

 during the working of the battery, becomes combined with water, but 

 the acid is easily and cheiply reconcentrated. In Sndl's, Daniell's, and 

 Grove's battery, the sulphate of zinc cannot be recovered, whilst in his 

 caloric battery the recovery was not difficult. The chairman expressed 

 the fear that the invent .r pro nised so much that he was no more likely 

 to perform it than to obtain pcrpetinl motion; indeed, if the invention 

 were not overstated, they would certainly be nearer perpetual motion 

 than they have ever been before. Mr. Varley suggested that as the 

 principal feature in the invention appeared to be the heating of the ma- 

 terials, it was not impossible that it might he as great a s ep in advance 

 as the introduction of the hot-blast in the manufacture of iron : this of 

 course remained to be seen. London Mechanics 1 Magazine. 



ILLUSTRATIONS OF MAGNETIC ACTION. 



The following is a partial report of a lecture recently delivered 

 before the Royal Institution of London, by Prof. Tyndall, "On some 

 of the Phenomena of Magnetism' 1 : 



The Crackle of Magnetized Iron. Here is a fine permanent mag- 

 net, competent to carry a great weight. Here, for example, is a dish 

 of iron nails, which it is able to empty. At the other side of the 

 table you observe another mass of metal, bent like the magnet, but 

 not, like it, naked. This mass, however, is not steel, but iron, and it 

 is surrounded by coils of copper wire. It is intended to illustrate 

 the excitement of magnetism by electricity. At the present moment 

 this huge bent bar is so inert as to be incapable of carrying a single 

 grain of iron. I now send an electric current through the coils that 

 surround it, and its power far transcends that of the steel magnet on 

 the other side. It can carry f>0 times the weight. It holds a 56 Ib. 

 weight attached to cadi of its poles, and it empties this large tray of 

 iron nails when they are brought sufficiently near it. I interrupt the 

 current: the power vanishes and the nails fall. 



Now the magnetized iron cannot be in all respects the same as the 

 unmagnetized iron. Some change must take place among the mole- 

 cules of the iron bar at the moment of magnetization. And one 



