Screntific Intelligence. 195 
an aperture at the top into which the molten lead is poured. The 
clay is then taken off and the lead driven home with a blunt chisel 
and hammer. It was in driving home the lead that the shocks were 
produced. ‘The sun was nearly vertical, and the thermometer at 
93° ; the ditch somewhat damp, and the pipes warm from the ac- 
tion of the sun upon them. The principle is no doubt that of gal- 
vanism, but as the cause is supposed to be entirely new, the plumber, 
(Mr. Johnson, from Philadelphia) having never known any thing 
like it during his long experience in that city, we should be glad to 
receive the opinion of scientific men upon it. 
We have since been informed, that after a heavy rain on the ensuing 
day, and the covering of a few feet of the pipes some distance above 
with earth, the phenomenon did not occur, nor has it since occurred. 
Remarks by a correspondent.—The phenomenon belongs, without 
doubt, to thermo-electricity. The exciting agent in the voltaic series, 
(for the chain of pipes with interposed lead soldering, may i be 
considered as such a series,) was made active by the intense heat of 
the sun. The pipes being of a black color, probably acquired a tem- 
perature much above that of the surrounding air ; they were probably 
also unequally acted on in consequence of their lying in a ditch. 
% ¥ * * 
We agree entirely in opinion with our correspondent, and cannot 
doubt that much of terrestrial and atmospheric electricity arises from 
similar natural galvano-electric combinations existing in the various 
arrangements of matter.—£d. ge 
3. Test for lead in oil of Vitriol, by 4. A. Hayes.—Commer- 
cial oil of vitriol often contains much sulphate of lead, to detect which 
and separate it in part, a few drops of strong muriatic acid may be 
dropped into the cold acid, an opaline, or milky appearance, indi- 
cates the presence of a minute portion only ; if considerably con- 
taminated, a precipitate falls, from which the clear acid may be de- 
canted. This effect seems to depend on the insolubility of chloride 
of lead in cold sulphuric acid; when heated, the acid dissolves it. 
Muriatic acid in water, readily dissolves and decomposes sulphate of 
lead ; the solution containing free sulphuric acid, may be boiled a 
long time without decomposition. By evaporating the liquor and 
heating the salt, decomposition of the chloride is effected. Com- 
mercial oil of vitriol dissolves much more sulphate of lead, than con- _ 
centrated sulphuric acid does ; the result of one experiment gave 
vows parts. 
