describing the properties of a salt, he guards against any error that may arise from the presence of an uncombined portion of the acid or base. And when he alleges of any element that it has a certain atomic weight, and unites with such and such equivalents of other elements, he does not mean that the results thus expressed are exactly the results of any one experiment; but that they are the results which, after averaging many trials, he concludes would be realized if absolute purity could be obtained, and if the experiments could be conducted without loss. His problem is to ascertain the laws of combination of molecules, not as they are actually displayed, but as they would be displayed in the absence of those minute interferences which cannot be altogether avoided. Thus all Abstract-Concrete Sciences have for their object, _analytical interpretation_. In every case it is the aim to decompose the phenomenon, and formulate its {87} components apart from one another; or some two or three apart from the rest. Wherever, throughout these Sciences, synthesis is employed, it is for the verification of analysis.[8] The truths elaborated are severally asserted, not as truths exhibited by this or that particular object; but as truths universally holding of Matter and Motion in their more general or more special forms, considered apart from particular objects, and particular places in space. The sub-divisions of this group of Sciences, may be drawn on the same principle as that on which the sub-divisions of the preceding group were drawn. Phenomena, considered as more or less involved manifestations of force, yield on analysis, certain laws of manifestation which are universal, and other laws of manifestation, which, being dependent on conditions, are not universal. Hence the Abstract-Concrete Sciences are primarily divisible into—the laws of force considered apart from its separate modes, and laws of force considered under each of its separate modes. And this second division of the Abstract-Concrete group, is sub-divisible after a manner essentially analogous. It is needless to occupy space by defining these several {88} orders and genera of Sciences. Table II. will sufficiently explain their relations. * * * * * TABLE II. ABSTRACT-CONCRETE SCIENCE. Universal laws of forces (tensions and pressures), as deducible from the persistence of force: the theorems of resolution and composition of forces. Laws of forces as manifested by matter in masses (MECHANICS) that are in equilibrium relatively to other masses and are solid. (_Statics._) and are fluid. (_Hydrostatics._) that are not in equilibrium relatively to other masses and are solid. (_Dynamics._) and are fluid. (_Hydrodynamics._) in molecules (MOLECULAR MECHANICS) when in equilibrium: (_Molecular Statics_) giving statical properties of matter