General doctrines comprehend whatever belongs to heat, light, attraction, & Electricity; because the influence of these substances may extend to all bodies whatsoever. All other individual substances in the world fall under the name of particular bodies. A simple body is that which has not been decomposed; a compound body is made up of two or more diferent bodies, either simple or compound. The number of simple bodies is about 50 at present, tho' some of them may hereafter be decomposed, & the number thereby lessened. Divis. 1st Chemical Attraction is the kind of Attraction wh we shall particularly notice in like Attr.; wh acts on particles, & at insensible instances & is of 3 kinds Aggregation, Affinites, & Cohesion. The Ancients believed that Air, Earth, Fire, & Water were the four simple elements in Nature, but all of these have been decomposed by Modern Chemists. A musket ball is an example of a body composed of homogenous or similar particles, I.E. particles of lead. And a ball of brass is a mass of hetrogenous or diferent particles, I.E. of Copper & Zinc. The Constituent partsof a body are the simple elements of which the body is composed, & into wh a body may be separated by decomposition, as Copper & Zinc are the Constituent parts of brass. The integrant parts of a body are such pieces of it as may be obtained by a mechanical operation, as by cuting a piece of bread, or by rasping a brass ball. We decompose a body into its constituent parts, & divide it into its integrant parts. The terms hard, soft, friable, denote only diferent degrees of Cohesion in a body.

Mercury does not adhere to a glass tube, when immersed in it, because its Cohesion is stronger than its attraction for the glass. Water adheres to a glass tube when put in it, because its attraction for the glass is greater than its cohesion: per the reason above Mercury assumes a spherical surface, which it is extremely dificult to prevent, the reverse takes place with water.

Heat & Liquid are principles used to overcome Cohesion. Heat possessing a high repulsive power, separates the constituent parts of a body to such a distance that their mutual attraction is destroyed. (Note Dr Caldwell objects to the theory of Repulsion,as being unfounded in Nature.) The mutual attraction existing between the particles of a solid & the particles of a liquid overcome the cohesion of the body; this process forms a solution, & in this way, a fluid dissolves a solid, i.e. by overcoming its Cohesion. In the same way a body is dissolved by rain, & by another solid, I.E. by the influence of affinity overcoming its cohesion. In a few cases, the affinity between the particles of 2 Solids is so much greater than the individual cohesion of the said solids, th they unite & form a new Compound. When Salt has been melted by heat, as soon as the heat is withdrawn, the Salt is restored to its solid form; if it returns slowly & regularly it will form itself into Chrystials & this is called Christilisation. But should the heat be suddenly removed, & the solution very quickly restored to a solid, then the figure will be without any determinate form, or angle. Thus, should lead after being very hot, be suddenly removed from over the fire, & placed in a very cold place, it will return to a solid, in the form of an irregular mass, without having any determinate measures. When the cohesion of a solid has been destroyed by the affinity of another substance, it willreturn to its solid state as soon as they other substance is removed, & it usually sinks to the bottom of the vessel in the form of a white powder. Chemical Affinity is the force by wh diff. particles are united in one body. When two or more boddies by the influence of Chem. Attr. are so united & assimilated in their particles as to form a homogeneous mass; the process by wh this is done is called Combination; thus, when we dissolve a piece of Salt in a glass of water so as the salt to become invisible, the process is called a Combination. A mixture is a mere mechanical union of the particles of two boddies, in wh case the particles altho intimately blended yet exist apart & may be easily known by the muddy colour, wh mixtures generally have. Thus if we put a quantity of sand or clay into water, & stir them together, we have a mixture whi may be separated by a mechanical operation called Filtration. The process by wh the ingredients of a Combination are separated is called Decomposition, & if this Decomposition has been performed with the view of discovering the constituent parts of the compound, it iscalled Chemical Analysis, & when this decomposed substance reproduced by the union of its constituent parts, the operation is denominated Chemical Synthesis.

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1. Probably Wilhelm Hisinger .

2. Probably William Irvine .