Electricity of Steam. 459 



tained when it was held much higher; and indeed sparks 

 were obtained by holding the conductor entirely out of the 

 cloud of steam, and at a distance from it, for the air in the 

 wooden shed in which we operated became speedily electrical 

 throughout. The electricity was positive. 



3. The steam in the boiler was now gradually run down to 

 see how the electrical condition would vary with the pressure. 

 At forty pounds per inch the sparks became much less, the 

 largest not reaching three inches. At thirty pounds the largest 

 spark did not reach two inches; at twenty pounds it became 

 barely an inch ; at ten pounds not more than from one-fourth 

 to one-half of an inch; and at five pounds per inch pressure 

 the spark was hardly perceptible. But if at any pressure the 

 valve was held down a few minutes so as to suffer the steam to 

 accumulate and then suddenly opened, there was always a 

 great increase, for an instant, of the electrical effects. 



4. Another boiler, that of the Lightning engine, which had 

 also just come in from a trip, and had its steam blowing off 

 forcibly, at a pressure of fifty pounds per inch, was now tried 

 in exactly the same way as the Wellington. On holding the 

 pointed conductor in the steam, whether regularly blowing 

 off at the valve or escaping with great rapidity from the sud- 

 den lifting of the valve, it did not yield a spark more than 

 one-fourth of an inch long. We then blew a quantity of 

 water out of the boiler of the Lightning until it barely covered 

 the tubes inside, and on afterwards testing its steam blowing 

 off at fifty pounds per inch, the spark was found increased to 

 nearly two inches in length. The steam of the Lightning 

 was, however, much less electrical than the steam of the Wel- 

 lington at the same pressure, under all the circumstances of 

 our experiments. 



5. The strong current of steam and water issuing from the 

 boiler of the Lightning when the water was blown out of it 

 as just stated, was tested for electricity, but no indications 

 could be perceived whatever. 



6. A very large conductor had been provided, made of 

 zinc two-inch tubing, in this way, — three rings were made of 

 this tubing, respectively three feet, two feet, and one foot 

 diameter. These rings were attached 

 to each other a foot and a half apart by 

 side pieces, so as to form a hollow frus- 

 tum of a cone, three feet high, with 

 ends three feet and one foot diameter 

 respectively. The inside of this cone 

 was laced across with copper wire, and 

 the whole bristled with pointed wires in 

 every direction. By means of a long 



