MMiscellanies. 207 
that would otherwise, in many instances, strike the steamboats loaded 
with so much iron; on coming in contact with the moist and heated 
column of steam, which ascends above the boats, immediately diffu- 
ses itself through the column of steam, and passes to the water with- 
out communicating any shock, or, in other words, the ascending 
steam performs the office of a Franklin rod.” And again, “The 
stream being in such a case a much better conductor than the tron of 
the boat, the Electricity will always take the steam tn preference to 
striking any part of the boat, and this it will do in so diffused a 
manner as never to be perceived or felt.” It is to be inferred 
from the foregoing, that the safety valve of a Low-Pressure boat is 
to remain open during a thunder storm, so that the steam may rise 
above the boat and “ perform the office of a Franklin rod.” 
It is clear then, that by furnishing this ‘ Franklin rod” the electri- 
city is not only invited but actually introduced into the steam in the 
boiler. Facilis descensus Averni, &c., the consequence of which 
is that a large quantity of caloric is evolved, which enters into the 
steam. ‘The sudden expansion produced by this heat, may be so 
great that the boiler cannot resist it and an explosion is unavoidable. 
This sudden expansion, coupled with the additional quantity of steam 
which may be produced by the electric heat transmitted through the 
steam to the water, is we think, amply sufficient to cause an explo- 
sion. From these remarks, it appears, that steam so far from pro- 
tecting steamboats from the effects of lightning, has rather a tenden- 
cy to produce them. Probably one cause of their exemption from 
accidents of this nature, in addition to that assigned by the Editor in 
his “ Remarks,” is their want of masts. Their chimnies, may pos- 
sibly not be sufficiently elevated to determine a cloud charged with 
electricity. With respect &c. Geo. ScHLEy. 
6. Sulphuric Acid.—The Editor or any of his numerous scien- 
tific correspondents will much oblige an “ Inquirer” if they will give 
the reasons for, and point out the sources of failure in the manufacture 
of sulphuric acid. Every chemist practically engaged, is aware, 
that although the same chamber and the same quantity of sulphur 
and nitre is used, yet the product of acid is extremely fluctuating. 
The books are unsatisfactory on this point. Gray in his “ Operative 
Chemist” says, ‘as the cause of this circumstance (viz. the acid not 
being condensed) was not known, it was attributed to the chambers, 
-which were said to be sick and would not work.” 
