96 G. F. Firzgzratp—On the Superfical Tension of Fluids. 
duced. Any such assumption as that the electrical distribution would produce 
the observed electrical potential is evidently inadmissible, because then the effects 
would vary with the forms of the surfaces, which is not the case. Hence, if x be 
the quantity of electricity employed in producing one electro-chemical equivalent, 
and if n be the number of such equivalents in presence of one another per unit of 
area of surface in contact, andif A be the area of contact, and « the electromotive 
force of contact, and T the superficial tension per unit of length, we have the two 
equivalent expressions for the superficial energy, 
TA=n.x.A «. or 
T=1ye. 
To approximate to a numerical calculation we must make some assumption. Thus, 
if we take the case of water, and assume N to be the total number of electrochemical 
equivalents in a gramme, and if we employ the C. G. S. system of units, 
a n 
T=106.7-6 
and if we assume T=-08 gr. per centimeter, or=78°5 dynes per centimeter, and 
é 107 
s«=10' or the tenth of a volt, we have Teast and consequently 
é . 
i, FSS) 
Row 1S LO SPB lO, 
so that if this were a surface of unit area, and thickness @ so small that all the 
particles are within reach of the surface, we should have n=Ne, and consequently 
C= eorlOme 
which approximates towards the quantities obtained by other methods. The most 
doubtful assumption I have made is that the electromotive force of contact of air 
and water isa tenth of a volt, but this is not impossible. 
I conclude, then, that superficial tension is solely due to this chemical attraction 
of dissimilar substances, as some part of it, at least, must be due to this cause which 
produces a potential energy of the masses depending directly upon the area of the 
surfaces in contact. I may mention that it seems to me likely that frictional 
electricity is due to a similar cause, and that it may be compared with Maxwell's 
experiment of the electrical current produced by altering the surface of mercury. 
In the same connexion compare Mr. Clark’s experiments, as published in Wiede- 
mann’s Annalen der Physik und Chemie., Neue Folge, Band II., on the electrical 
potential of water driven through capillary tubes. 
JU, 
[intend to devote this second part of my paper to developing the possible ¢on- 
nexion between surface tension and muscular action. 
It is known that muscles when they contract, alter little or not at all in bulk, and 
it seems, therefore, likely that the alteration in arrangement that they undergo is a 
change of superficial area of their component parts. Now, if we assume a muscle 
