The menstruum is supposed to _act_ by "chymical attraction," from having "chymical affinity" on the involved "chymical solid," which enables it to draw out the elementary atoms of the solid: whereas the _inert_ menstruum does nothing; it is but an interstitial recipient for the atoms to be forced into, as they become centrifugally forced out of the solid. And because the atoms of a body are of different sizes, some make novel interstices, and thus expedite the dissolution. Only by increasing the number and kind of interstices, can diluting a menstruum with water increase what is imagined to be its solvency. Neither chymical properties, nor chymical strength of a fluid, if it had any such, could be increased by dilution, and the stronger should dissolve that which the weaker is said to dissolve. The contrary supposes that the force which breaks a stone is too strong to break a nutshell. Mechanical dissolution by the centrifugal pressure is independent of _chymicalities_. _Gastric solution_ is effected similarly: the juice has none of the chymical properties of Liebig, nor does ingestion stand in need of the living principle of Coombe; the former are imaginary, the latter is denied from gastric solution taking place in a tea-cup. The gastric juice is an interstitial receiver of the elements of the pulp, when forced out by the centrifugal pressure into the gastric menstruum, as those of soap into water. The pulp and its _striæ_ are disunited, mechanically decomposed, not abraded: some of its elements escape into the air within the stomach, which, by disturbing the equilibrium within, promote irregularity of pressure on the outside of the sac, which causes the _pliæ_ to be in the peristaltic motion, supposed to be caused by the stomach stimulating itself. The same circumstances take place within and without the intestines. The whole process of digestion is dynamic, in which the only stimulant is pressure.