they are compound. It cannot be doubted that, as the science advances towards perfection, many of them will be found so. Very probably a new set of simple bodies will offer itself, of which we are at present ignorant. These again may perhaps be decomposed, till at last, when the science has reached the highest degree of perfection, those really elementary substances will come into view, of which all bodies are ultimately composed. Whenever this shall happen, the list of simple substances will probably be reduced to a much smaller number than at present; till this however does take place, we are entitled to consider them as simple substances, according to the present state of our knowledge. Their number amounts now to fifty, including those unconfinable agents called heat and light. They may be conveniently arranged in the following order. SECT. II. CLASSIFICATION OF SIMPLE SUBSTANCES. DIVISION I. SIMPLE SUBSTANCES PRODUCIBLE BY ART. 2 IMPONDERABLE SUBSTANCES. Light PONDERABLE SUBSTANCES. 3 Combustible bodies destitute of metallic properties. Sulphur 28 Combustible bodies, possessing metallic properties, called Platina Gold Silver Copper Iron Lead Tin Zinc Mercury Tellurium Antimony Bismuth Manganese Nickel INCOMBUSTIBLE BODIES. 6 EARTHS. Silex Zircon Yttria Magnesia. 5 ALKALIES. Barytes Strontia Lime. DIVISION II. 6 SUBSTANCES NOT YET PRODUCIBLE BY ART, BUT ANALOGICALLY CONSIDER ED AS SIMPLE. Oxygen Hydrogen Muriatic radical Fluoric radical Boracic radical. Such are the bodies which the corpuscular theory considers as simple, and to which chemical writers have given the appellation of RADICALS. Some can only be exhibited to our view in their simple state; others, on the contrary, have not yet been successfully exhibited experimentally, uninsulated. Their existence can nevertheless be inferred from the analogy of certain general and wellestablished facts. The impossibility of producing them arises no doubt from their great tendency to unite with other substances, and from the opportunity they meet with at every separation. NATURE OF CHEMICAL ACTION. PART V. THE different actions which result from the proper application of the bodies enumerated before, when either in a simple state or when combined together, are founded on certain agencies inherent in all matter. This we take for granted, and consider as a fact; without pretending to explain how bodies came to be possessed of these agencies, or how they are capable of exerting them. Philosophers therefore express the unknown causes which produce these changes, by the metaphors of ATTRACTION and REPULSION. Before we attempt to give an explanation of these terms, we shall endeavour to exemplify what is understood by chemical action in general. We therefore flatter ourselves that the following simple facts intended for that purpose will not be deemed frivolous; our chief object being to advance in this place some palpable, positive, and negative proofs, which show, that whenever chemical action takes place, the properties of bodies become altered, and their individuality destroyed. SECT. I. INSTANCES OF CHEMICAL ACTION. EXPERIMENT I. LET a small portion of marble or chalk, reduced to powder, be diffused in a quantity of water, the marble presented to the water will fall to the bottom of the vessel and remain unaltered. On shaking up the whole, a white turbid mixture will be formed, but on letting it stand undisturbed, the marble will again fall to the bottom, and the supernatant fluid remain transparent and unaltered. In this case no chemical action has taken place, for neither the properties of the marble nor the water are altered if examined chemically. EXPERIMENT II. If we let fall a like quantity of marble or chalk into another fluid, called an acid; for instance, into vinegar, or nitric, muriatic, or sulphuric acid; the effect then will be different: a violent action will take place the instant they come into contact, the marble will gradually disappear in these fluids and become more or less dissolved, and a transparent solution will be obtained. In this case a chemical action has taken place between the bodies brought into the sphere of action, for the properties of both the substances can no longer be distinguished, their appearances are more or less altered, and their individuality destroyed. REMARK....Chemical action is reciprocal. It cannot be said that the acid acts on the marble, or the marble on the acid; convenience of expression has permitted the whole of the action to be attributed, without misconception, to one of the substances, when the effect of the action is to be examined instead of the action itself; hence we say, vinegar acts upon marble, water acts upon salt, &c. It were to be wished that the action of different bodies upon each other could be referred to a few general laws, |