ORGANIC ANA LYSIS.—Under the term organic analysis are included the various me thods of discovering the constituent parts of substances, formed either directly by the vital actions of organized beings, or indirectly by subjecting the products of such actions to the further operation of re-agents. To treat the subject in its full extent would, however, be foreign to the purpose of the present article, in which I shall confine myself to the analysis of the products of animal life, and particularly of those combinations liable to be met with in the human frame.
In this analysis two distinct objects present themselves : the first consists in the determin ation of the proximate principles which enter into the constitution of the substance to be analyzed, and the second in the discovery of the eleinentary composition of the different proximate principles.
I shall therefore in the first place describe the various means by which we recognize the occurrence of the more important proximate animal principles, and determine as far as we are able the quantities in which they may be present : this portion of the subject I shall con clude with a brief sketch of the general method of analysing the principal secretions in the healthy and more ordinary morbid conditions,— for more ample details I must refer to the articles specially devoted to the history of each secretion. I shall then, in the second place, proceed with an outline of the processes best adapted to the ultimate analysis of organic bodies in general.
To the pathologist the first of these objects is the most important, and it is he alone who possesses the extensive facilities requisite for investigating the different varieties exhibited by the secretions in disease, whether these varieties present themselves in the undue prevalence of one or more of the proximate principles, the undue deficiency of any of them, or the unu sual occurrence of any of them among the secretions, or in the tissue of particular organs.
The value of such information to the enlightened practitioner is sufficiently evident, for an accu rate and ready mode of appreciating these changes not only affords him some of the most unerring indications of the nature and progress of disease, but enables him likewise to appre ciate the effects and influence of the remedial measures that he may think it needful to adopt. To the chemist, on the other hand, belongs more appropriately the task of determining what ought to be considered as really proximate prin ciples, of insulating them in a pure state, and finally of ascertaining their elementary coni position by ultimate analysis.
In every case, before proceeding to analysis, it is desirable, nay, in the present state of science almost necessary, to subject the mate rial to a careful microscopic examination ; for although this does not of itself suffice to deter mine the chemical nature of the substances with which we have to deal, it yet furnishes us i with the most important preliminary information we can acquire, and is frequently, owing to their close chemical relationship, the only means of ascertaining what is the form of the azotised constituents of the body with which -we have to .clo. In truth, unless a chemist be likewise in ome degree acquainted with the resources daced at his disposal by the microscope, he is out half fitted for the task of organic analysis.
For the necessary information respecting the qiinute structure of the different products of iiimal organization, I must again refer to the arious articles on the subject in different parts f this work. (See Btoon, CIIYL E, MILK, II3CUS, Pus, SALIVA, URINE, &C.)