1817.) On the Chemical Phenomena of Heat. 427 
area P’NC p’ P’ represents the latent heat. By latent heat nothing 
more is meant than the heat which is attracted by a particle or 
number of particles, and which is .*, not communicated to any 
other body, except of a lower temperature ; the increment of the 
area P’N C p’ P’ is the capacity corresponding to any change of 
temperature ; p g — 7 q, or the excess of density of the caloric at 
any distance, above its density xg = 7 s inthe ambient medium, is 
a measure of the calorific repulsion, or the tendency which the 
caloric will have to produce expansion. If the centripetal force really 
1 F . 
@ Gea» then the distances from the surface of a particle of matter 
being in harmonial progression, this will be in geometric. The centri- 
1 ‘ lala : 
petal force « --=7, and the centrifugal « » it immediately 
dist n + m 
follows that the particles which constitute solids are in actual con- 
tact with each other, and that the phenomena of expansion and 
contraction arise from an alteration which takes place in their ar- 
rangement. Let ABC DEF (Fig. 3) represent a number of. 
spherical particles mutually attracting each other. They will arrange 
themselves in such order that straight lines joining their centres 
shall form equilateral triangles; for then the sum of their mutual 
actions upon each other will be a maximum. ‘The introduction of 
any repulsive power, whose intensity diminishes more rapidly than 
that of the centripetal force, will produce an alteration in the ar- 
rangement of these particles, which occasions an expansion of the 
mass. Let ABC D (Fig. 4) represent four = and similar par- 
ticles of matter; with centre B and radius B C describe the semi- 
circle A DC, the sphere D may evidently roll upon B, and the 
locus of this centre will always be in the semicircle, and its initial 
motion will always be in the direction of a tangent at the point D. 
Join AD, BD, CD, and draw x y a tangent at D; at Q erect 
the | RQ to represent the centripetal, and Q U the centrifugal 
force at the surface of O; draw the curves R W, U T G, whose 
ordinates represent the intensity of the forces at all distances; draw 
the same curves belonging toA; in solids RQ =>MK>UQ= 
L. K .*. the particles must be in contact. W D = centripetal force, 
which tends, at the distance DC, to bring D and C in contact; 
and ST represents the force which tends to separate them; N D is 
that force which tends to bring Dand A into contact, and p O that 
which has a tendency to separate them; the differences between 
these forces are the powers which tend to put the particle D into 
motion. Represent W D — ST by DH, and N D — pOby DF, 
and at H and Y draw HG, FE {| thetangent. Then by the re- 
solution of forces, E D and D G are the two which keep the par- 
ticle D in equilibrio, or tend to put it in motion EF, GH // 
DB preserve the contact with B ; when the particle D is stationary, 
i. @. the body has attained the temperature of the surrounding me- 
dium ED = DG;; «. if D were very near C when the temperature 
