186 Steam as (1 moving power.

The experiment of Perkins, whereby a soft malleable wrought iron piatg;
revolving at an immense velocity, not only cuts its way Into a file applied
thereto, but elicits such a coruscated blaze by the combustion of the steel
and iron abraded, as to astonish even the scientific beholder, furnishes evi.
dence of the result of the compound operation of friction, and consequent
increase of specific gravity ofthe metals abraded.’ Not the least apparent.
ly astonishing part of this performance is, that of the hard steel file being
cutby the comparatively soft malleable iron plate; but all astonishment,
will, no doubt, cease on remembering that the density or hardness of the
file as compared with that of the revolving plate, is in a much less ratio
than the area or the rubbing part of the latter, as compared to the area of
that part of the file coming in contact or rubbed therewith. Fbr example,
the file is probably not twice as hard as the revolving plate. whereas the
grinding surface of the latter probably exceeds the area of theifile ground,
one hundred times; hence the wear of the file is inevitable. I cannot
doubt but that the particles of wrought iron abraded and excited into coin-
bustion, greatly exceed in number the atoms of steel. This is not discov-
able on superficial observation by reason of the great diameter and inreas-
ed surface of the revolving plate, viewed in connection with th-e surface or
quantity of the file detached in the operation.

That a soft elastic substance will wear away more dense and inelastic
matter, is verified by the well known fact that the cuticle orscarf skin of
the hand wears away both cast and wrought metal hand rails; and what
appears‘ still more astonishing, but isvnevertheless well authenticated,*is that
of the marble steps leading to some favorite saint, having been worn quite
hollow by the friction of the naked feetand knees of pious devotees.

The third theorem partalres of positive and negative qualities, for each
abstractedly considered neutralizes the other; in fact, the question admits
of no other than a false solution, unless the intermediate cause and- effects,
dilatation and the sensible caloric thereby becoming latent, form compon-
ents pf the question,.viz.,. that high pressure steam, when applied expan-'
sively, as amotivapower; is less economical than atmospheric steam when
not permitted to expand till the piston» has completed its stroke. , There
certainly appears, at first view,..somethinc__r very peculiar about highly elas~
tic steam when expansively applied, for the fuel saved is positively just so
much fuel lost; paradoxical as it may appear, it is reallyno paradox, but
is in strict accordance with the working of nature’s laws; and I sincerely
wish that all other supposed paradoxescould be as readily cleaned up.

_ In practice, we observe that every additional atmosphere’s elasticity steam
18 generated at, the time is shorter than was occupied in generating the
previous atmosphere; even when equal quantities of combustible matter
are decomposed, or equal increments of caloric are evolved in equal peri-
ods of time; in this case the saving of fuel accruinrr will be in the exact
mil‘) ‘O the time SW03. and is exclusively the resnli of steam of a given
number of atmospheres elasticity containing less Water than is contained
in the same number of volumes ‘of atmospheric -_ steam, the in,evj¢ab]e con;
sequence of latent heat being evolved in a sensible state as the steam’s den-
i8;1t};];1;t;)ert;s:}S1;e \t;l;1:<:i: caloric, of course, increases the ste'a_m’s'éla sticitypand
I j 1 Q _ V p _e measure or amount offuel saved In genenatmg_h1gh-
y e a..tlC steam, but is unfortunately lost when such steam (as Wlll be here-
inafter shown,) is applied expansively. ‘Atmospheric sieami re-gistersr ra
tempergture of 212°,‘ steam of ten atmospheres elasticity of 358°, ‘twenty:
of 418 , thirty of -457 °, forty of, 486°,and that of fifty atmospheres elagu.
°-"Y “ *5‘-m,P¢1'3m1'9 Of 510°; Here then the quantity of — sensiblerc-,al.ori«c;in
each-atom of steam‘ of 510° temperature produces apower infinitely -green