VOLUMETRIC ANALYSIS. l'ofitatetrica/ Analysis. In chemistry, analysis comprehend. that series of operations by which a compound body is resolved into its constituents. Analysis may be qualitative, and have for its object the were ascertaining of the number and nature of the constituents, or it may be quantitative, which as well includes the determination of the amount of each ingredient. Quantitative analysis is based upon the great chemical law of definite combining proportions, and may be proceeded with either in a gravimetrical or in a volumetrical manner ; that is, a body may be isolated and weighed alone in a balance, and its quantity ascertained ; or it may be separated by, and weighed in combination with, another body, whose combining proportion is well known : such is the gravimetric method. The balance, the instrument used for measuring the gravitating force of the compound, may, however, be in part or wholly discarded, and the amount of a constituent of a com pound be ascertained by noting the volume of a liquid which is required to be added to the compound before a given effect i3 pro duced : such is volumetric analysis. Gravimetry is more generally applicable, but requires an exceedingly delicate nce, with perfectly accurate weights, great skill in manipulation, and the expenditure of a considerable amount of time. Volumetric analysis is auly applicable to a limited extent ; and the liquids referred to, or standard solu tions as they are called, sometimes require considerable care in their preparation ; but no elaborate apparatus is necessary. The operation is simple. and easy of execution, and may usually be performed in one-tenth or one-twentieth part of the time necessary for a gravimetrical experiment Volumetrical analysis seems to have first sprung from Richter's observations on neutral saline solutions, a research which much aided the discovery of the laws of chemical combination. Quantitire estima tion by the balance, or restricted gravimctrical analysis, existed prior to that time, and was constantly appealed to in determining the truth of these laws, because the balance was already well known, and its indications could be relied on. Until chemistry began to be
applied in the arts end manufactures, there was little or no demand for expeditious analytical processes ; even the volumetrical processes of alkalirnetry, scidimetry, and chlorimetry, introduced by Descroizillea, and improved by Gay-Lussac, Dalton, and Faraday, for a long time stood elope ; and not until within the last ten or fifteen years did the operation of analysis by measure attract any particular attention, or seem likely to aid, much leis to any extent supersede, the old method of Siuce that time, the tendency has been in the opposite direction ; and now many of the elements, as well as the more commonly occurring proximate principles, can be estimated by volumetric methods. Oases have been almost exclusively analysed volumetrically, but, requiring special and peculiar treatment, their examination is described under Ossourrnic ANALYSIS, which is generally looked upon as a distinct and separate branch of chemistry.
An enumeration of all the processes of volumetric analysis would require more space than can be devoted to such a subject in this Cycloptedi. : nor would such a list be of value for any length of time. The masterly researches of Bunsen and others have already systema tised and extended the applications of many of these processes; in a few years, therefore, it is hoped that an approach to classification may be attained, and that the present inconvenience of having to make, and the difficulty of keeping, so many standard solutions, to a great extent will be got rid of. Moreover, several volumetric methods have already been treated of in this Cyclopredla [AticAtimrrev ; ACIDIMETRY ; ASSAYINO ; CIILORIIIETUY ; COPPER; SOAP-TEST; TANNIN; UREA], so that the subject need only be generally treated of here.