270 



ELECTRICITY. 



Acid solutions, in general, give a spreading, or 

 matted deposit ; alkaline solutions, a bristling one. 

 The contact of the coating is promoted by working 

 the solution hot. The article should be pickled, 

 scrubbed with sand, washed, scrubbed with a portion 

 of the depositing solution, and then placed in the 

 depositing-trough ; after deposition, the article is 

 washed, and dried in hot mahogany sawdust. Com- 

 plete protection from rust, and a satisfactory coating 

 for any purpose, are given by the use of the acid- 

 depositing bath subsequent to that of the alkaline 

 bath. 



. The subject-matter of this paper is illustrated by a 

 calico-printing roll, weighing 125 Ibs., with 29 IDS. 

 of deposit upon it ; ana by twenty other results of 

 the inventor's improvements. 



The coating by means of the author's method of 

 working is superior to that of any other known pro- 

 cess. The invention is applicable to the prevention 

 of rust, the coating of plungers and other portions of 

 machinery, and the lining of cylinders, etc. ; also 

 applicable to architectural and other castings, and to 

 many purposes which require the strength of iron 

 and the beauty of brass. 



Magnetic Changes of Iron. The Philosophi- 

 cal Magazine, for September, contains a paper 

 by G. Gore, F. E. S., detailing many experi- 

 ments made upon iron at different tempera- 

 tures to determine the changes caused by heat 

 in its molecular and also its magnetic condition. 

 His results may be briefly stated, as showing 

 that, on gradually heating a bar of magnetic 

 iron, when it attains a moderate red heat, a 

 succession of small movements takes place 

 among its molecules, and that on cooling it a 

 succession of opposite movements occurs. A 

 red heat in the middle of such a bar largely 

 diminishes but does not entirely prevent the 

 transmission of magnetism along it ; while in 

 the process of cooling the magnetism of the 

 iron is greatly increased. The same peculiari- 

 ties were noticed in steel, cast-iron, and nickel. 

 Gore closes his communication by remarking 

 that the phenomena described illustrate a very 

 general (or universal) property of matter, viz., 

 that every substance, even those of the simplest 

 constitution, when acted on by a single exter- 

 nal force, possesses the power of dividing the 

 influence of that force in soch a way that, in- 

 stead of producing only one force, or one effect, 

 it produces several; or, stated more briefly, 

 matter has a universal property of dividing and 

 multiplying forces and effects. He adds that 

 the changes produced by heat in even so simple 

 a substance as iron were so numerous in some 

 of his experiments as to make the metal seem 

 endowed with vitality. 



Electrolysis of Nitric Acid. Some curious 

 effects in the electrolysis of nitric acid, of 

 various degrees of dilution, are given in the 

 Mechanics' Magazine, for May. When a very 

 dilute acid is operated on, hydrogen only is 

 evolved at the negative pole, and no secondary 

 product is formed in the liquid contained in the 

 negative compartment. "With a less dilute 

 acid, that is, one with about 125 equivalents of 

 water, hydrogen is first given off, then a little 

 nifrogen, and the liquid is found to contain 

 traces of ammonia. In the case of a stronger 

 acid with only 15 equivalents of water, while 



oxygen is first given off at the positive pole, no 

 hydrogen for some time tscapes at the nega- 

 tive, all that gas reacting upon and combin- 

 ing with the acid in the compartment, the 

 liquid assuming a distinctly blue color. After 

 some time, however, hydrogen mixed with 

 some nitrogen comes off, but soon gives place 

 to an evolution of binoxide of nitrogen, 

 which in its turn ceases, and hydrogen again 

 appears. In the end a good deal of ammonia 

 is found in the negative liquid and also much 

 nitrous acid. Nitric acid with two equivalents 

 of water gives off at first only binoxide of nitro- 

 gen, then hydrogen. Thus it appears that the 

 reducing action of hydrogen on nitric acid ac- 

 cording to the strength of that acid produces 

 nitrous acid, binoxide of nitrogen, nitrogen, 

 and ammonia. 



Electricity and Ozone. ITouzeau makes the 

 following deductions from a great number of 

 estimations -of ozone obtained by means of 

 Ruhmkorff's apparatus : 



1. The production of ozone is greater in air re- 

 newed from time to time than in confined air. 



2. It is greater at the negative than at the positive 

 pole. 



3. The production of ozone increases only up to a 

 certain point with the duration of the electric action. 



4. The ozone increases with the electric intensity. 



5. The ozone diminishes when the distance which 

 separates the electrodes increases. 



6. The production of ozone varies with the length 

 or surface of the electrodes. 



7. Other conditions being equal, the production of 

 ozone is greater by utilizing the effect of the two 

 electrodes. 



8. The production of ozone is equally manifested, 

 out of direct contact with the air, with metallic elec- 

 trodes, when these last are surrounded for their 

 whole lengths with tubes of thin glass playing the 

 part of insulating sheaths, whether the extremities 

 of these tubes are closed or not. 



9. Still the production of ozone resulting from the 

 passage of air over the naked metallic electrodes (di- 

 rect contact with the platinum wires) is greater than 

 that which arises from the passage of the air round 

 the same electrodes, when sheathed and closed (no 

 direct contact of the air with the naked metallic elec- 

 trodes). 



10. With closed sheathed electrodes the production 

 of ozone varies equally with the length or surface of 

 the metallic electrodes. 



11. The production of ozone increases considerably 

 with a diminution of the temperature at which the 

 electrification of the air is effected. 



12. All conditions being equal, the quantity of 

 ozone produced with a definite volume ot oxygen is 

 always much more considerable (about eight or ten 

 times) than that furnished by the same volume of 

 air. 



13. The ozone produced by the obscure electrifica- 

 tion of air is accompanied by small quantities of ni- 

 trous compounds, w.hile that which is furnished by 

 pure oxygen, under the same circumstances, contains 

 only traces. By attention to the conditions above 

 described, the author has been able to construct a 

 new apparatus, which he calls an ozonizer, and with 

 which, according to his statement, quantities of ozone, 

 hitherto unknown, may be prepared. 



A Cause of Error in Electroscopic Experi- 

 ments. Sir Charles Wheatstone, F. R.S., read 

 a paper with this title, before the Royal Socie- 

 ty in April. In the course of some experiments 

 on electrical conduction and induction, he had 



