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Water jet as a current carrier
iV'otfs and Comments.
212
[J. F. 1.,
upon t h a t on which it is deposited. Moreover, these t w o neutral points are not identical for the same solution. T h e present writer has s h o w n '~ that crystals f o r m e d from a current-bearing electrolyte are not affected by the eurrent, t h o u g h t h e y m a y be s o m e w h a t distorted b y the a c c o m p a n y ing h e a t i n g effect in the liquid. T h e foregoing seem to be all the properties of currentb e a r i n g solids and liquids that h a v e b e e n investigated. If any reader can s u p p l e m e n t this bibliography, the writer w o u l d consider it a favor if he w o u l d do so, a d d r e s s i n g him at the Central H i g h School, Philadelphia. A f t e r r e v i e w i n g w h a t has been done in this field, m a n y i n t e r e s t i n g research p r o b l e m s are s u g g e s t e d . Some of this work the writer has u n d e r way, and it w o u l d be well for i n t e n d i n g workers in this field to correspond with him in order that useless duplication m a y be avoided.
H E A T W A S T E FROM U N P R O T E C T E D STEAM PIPES. According to careful experiments made by Prof. S. P. Thompson, a square foot of uncovered steam-pipe filled with the vapor of ioo pound pressure will radiate and dissipate in a year the heat put into 3,7t6 pounds of steam by the economic combustion of 398 pounds of average coal. Thus, lo square feet of bare pipe corresponds approximately to the waste of 2 tons of coal per annum. A n o t h e r experimenter, testing the various materials employed for wrapping, ~oncludes that the saving in condensation effected with the best form of mica covering is nearly 88 per c e n t . - - t h a t is, calling the loss of heat with bare pipes IOO, the loss when wrapped with mica-packing would be 12. Asbestos covering seems to be considerably inferior to mica, and cements less desirable than either. W A T E R JET AS A C U R R E N T C A R R I E R . The danger from electricity, particularly for the firemen in directing a stream of water upon an object carrying electric current, was the subject of an article in a recent issue of Energie, of Berlin, recording the results of a number of tests. A man wearing wet shoes and standing on a wet plank flooring, threw a jet of water on an electrified plate. At 5oo volts and an aperture of 0"74 inch in the nozzle, he felt the current at a distance of 2)4 feet, and with an aperture of about 2 inches could not get nearer t h a n about 3 ~ feet. Under the same conditions, but with alternating current, he could not stay ~ i t h i n 8"2 feet, and at 3,6oo volts he had to remain at a distance of 26~/~ feet.
~P]ysical Review,
1 5 , No. 6, December, i9o2.
212
[J. F. 1.,
upon t h a t on which it is deposited. Moreover, these t w o neutral points are not identical for the same solution. T h e present writer has s h o w n '~ that crystals f o r m e d from a current-bearing electrolyte are not affected by the eurrent, t h o u g h t h e y m a y be s o m e w h a t distorted b y the a c c o m p a n y ing h e a t i n g effect in the liquid. T h e foregoing seem to be all the properties of currentb e a r i n g solids and liquids that h a v e b e e n investigated. If any reader can s u p p l e m e n t this bibliography, the writer w o u l d consider it a favor if he w o u l d do so, a d d r e s s i n g him at the Central H i g h School, Philadelphia. A f t e r r e v i e w i n g w h a t has been done in this field, m a n y i n t e r e s t i n g research p r o b l e m s are s u g g e s t e d . Some of this work the writer has u n d e r way, and it w o u l d be well for i n t e n d i n g workers in this field to correspond with him in order that useless duplication m a y be avoided.
H E A T W A S T E FROM U N P R O T E C T E D STEAM PIPES. According to careful experiments made by Prof. S. P. Thompson, a square foot of uncovered steam-pipe filled with the vapor of ioo pound pressure will radiate and dissipate in a year the heat put into 3,7t6 pounds of steam by the economic combustion of 398 pounds of average coal. Thus, lo square feet of bare pipe corresponds approximately to the waste of 2 tons of coal per annum. A n o t h e r experimenter, testing the various materials employed for wrapping, ~oncludes that the saving in condensation effected with the best form of mica covering is nearly 88 per c e n t . - - t h a t is, calling the loss of heat with bare pipes IOO, the loss when wrapped with mica-packing would be 12. Asbestos covering seems to be considerably inferior to mica, and cements less desirable than either. W A T E R JET AS A C U R R E N T C A R R I E R . The danger from electricity, particularly for the firemen in directing a stream of water upon an object carrying electric current, was the subject of an article in a recent issue of Energie, of Berlin, recording the results of a number of tests. A man wearing wet shoes and standing on a wet plank flooring, threw a jet of water on an electrified plate. At 5oo volts and an aperture of 0"74 inch in the nozzle, he felt the current at a distance of 2)4 feet, and with an aperture of about 2 inches could not get nearer t h a n about 3 ~ feet. Under the same conditions, but with alternating current, he could not stay ~ i t h i n 8"2 feet, and at 3,6oo volts he had to remain at a distance of 26~/~ feet.
~P]ysical Review,
1 5 , No. 6, December, i9o2.