972 TRANSACTIONS OF THE AMERICAN INSTITUTE. 



moment (March, 18G7,) pending at the Patent Office in Washing- 

 ton, waiting for a decision. 



Porter, of Philadelphia, had also (October, 1865, No. 50,774,) a 

 patent granted, where he uses a similar isolating arrangement, -and 

 an isolated point projecting out of the boiler — evidently, again, a 

 discharge of the exjjiosive electvidty. But he adds a long spiral 

 wire, such as' when v/ound around a wrought iron bar charges it 

 with magnetism by means of a galvanic battery, only the iron bar 

 and the battery are omitted, and the inside of the spiral is empty; 

 this spiral wire, now entirely useless, is at one end connected with 

 the boiler, and at the other isolated end is a disk attached, with a 

 few small points. It is evident from this whole arrangement that 

 the experiments and attempts were made, as it were, blindly, in 

 ignorance of the principle to be applied, and not clear about the 

 results to be arrived at. 



The apparatus was placed inside some steam boilers, hoping to 

 get rid of that dangerous explosive electricity — that cause of so 

 many disasters — and, it is said, that some unexpected result was 

 obtained, namely, it was asserted, that these boilers remained free 

 from incrustation, and that even scales already formed got loose. 

 Now this may be true in a few instances, and prove nothing for 

 the arrangement, as all practical engineers know how capricious 

 steam 1)oilers are in this respect, how some will form scale, and 

 others in perfect similar circumstances, and using the same water, 

 will not; how even the same boiler one season will be covered 

 with iiicrustation, another season will not form any scale Avhatever, 

 perhaps produced by the difference in the water in different sea- 

 sons, or l)y causes which we cannot always trace.' Then it is very 

 easy to place in the steam boilers some chemical substances, for 

 instance sal ammonia and gum catechu, the presence of which will 

 protect any boiler from incrustation for about three months. But, 

 whatever may have lieen the cause, to the Porter arrangement a 

 certain credit was given as an anti-incrustator. Some enterprising 

 gentlemen got hold of the patent, and resolved to form a stock 

 company and put the apparatus in the market. 



Then every man of science knows that to effect those repulsions, 

 even to a weak, scarcely perceptible extent, the most powerful 

 electro-magnets, charged by large galvanic batteries, are required, 

 magnets capable to carry, when attracting iron, a ton or more in 

 weight, and that the bodies have to be brought immediately 



