ANALYSIS, in a general sense, is the resolution of something compounded in to its constituent parts. Hence, ANALYSIS, in chemistry, is the separa tion of any substance into its constituent parts, with a view of ascertaining their nature, relative proportion, and mode of union. An instance of this kind is to he had in the decomposition of water, by which it is found that the constituent parts are hydrogen and oxygen, in the propor tion of fifteen parts of the former, and eighty-five parts of the latter. As every operation in chemistry is attended with a disunion of parts, the formation of new compounds is almost an invariable conse quence ; hence, the business of analysis is intimately connected with the whole of chemical science, and can be only tho roughly understood by one that is well versed in every branch of chemistry. On so extensive a subject, it is in vain to attempt laying down precise rules for the mode of operation generally. We may, however, observe that a compound, once formed, perpetually acquires the powers of an element, in being able to unite, un decomposed, with other bodies, simple or compounded, in various proportions ; and thus to produce new substances, in which the constituent parts often retain their original affinities, and in analysis again separate into their elementary substances. We may refer to nitrate of ammonia, which is a salt composed of nitric acid, ammonia, and water, each of which is it self a compound, but in this particular combination, it acts as an elementary body : thus, nitric acid consists of azotc. and oxygen : ammonia, of azote and hy drogen: and water, as we have seen, of oxygen and hydrogen : so that, in truth, there are only azote, hydrogen, and oxy gen, that enter into the combination of nitrate of ammonia; but in their simple state, they cannot be made to form the salt ; it is requisite that the acid, the al kali, and the water, should be first form ed, in order to get the neutral salt.
The business of chemical analysis is to resolve a body into its constituent parts; but the first question is, to determine, in every instance of analysis, whether the resolution should proceed to entire sepa ration into real elements, or only into those compounds which act as elements ; as in the case referred to, whetter the nitrate of ammonia should be resolved into azote, hydrogen, and oxygen ; or whether it should not first be reduced in to nitric acid, ammonia, and water. The
former mode is best calculated for re search, the latter for utility ; but a mix ture of the two methods is commonly adopted, where the proportion and nature of the compound produced has already been fully ascertained by previous experi ment. The most rigid proof of the accu racy of analysis is, to he able to produce the same compound, by uniting the identi cal parts which we have given as its con stituents. This Can rarely be performed in a manner perfectly satisfactory; hut it frequently happens that a substance may be produced that resembles the one ana lysed, by employing similar constituents, if not the identical substances. This proof even is almost totally wanting in the analysis of organised bodies, whether vegetable or animal, especially when re duced to their ultimate elements, and generally when only separated into their immediate constituents. The agents made use of in analysis are, heat, the electric and galvanic fluids, if they are two fluids, and the application of reagents or sub stances, which indicate the parts of the body to be examined.
ANsaysis, among logicians, is a me thod of tracing things backward to their source, and of resolving knowledge into its original principles. It is also called the method of resolution, and stands op posed to the synthetic method, or method of composition. The art of this method consists chiefly in combining our percep tions, and classing them together with ad dress ; and in contrivinga proper expres sion of our thoughts, sv as to represent their several divisions classes, and rela tions. This is clearly seen in the manner of computing by fipres in arithmetic, but more particularly al the symbols applied in resolving alge.Sraical problems.