116 Chemical Researches upon Diseased Milk, 



We conclude from these facts, that, in undertaking, with 

 any hopes of success, a du-ect normal analysis, we must first 

 be certain that we define, if not all the proximate principles 

 of any given organic substance, at least the principal of them, 

 respect being had to the importance of their properties, and 

 the great proportion in which they are held ; and if this cer- 

 tainty cannot be attained, and we do not recoil before the 

 troublesome labour, we must then seek for those proximate 

 principles which we judge to be the most analogous to those 

 we wish to separate from the substances in which they are 

 most abundant, most isolated, or in the state of easiest se- 

 paration ; so that we may study their properties, and select 

 those essential characters which will be recognised with 

 most facility, and which will serve as the distinguishing cha- 

 racter whereby we may judge whether the separated principles 

 of any substance of which we are desirous of making the nor- 

 mal analysis, are identical or only analogous to the first. 



There is one consideration which ought not here to be 

 omitted, viz., that there are sometimes globules, and these 

 occasionally so small, that, simply suspended in animal fluids, 

 they are perceptible only with the help of a lens or the mi- 

 croscope. In all cases, therefore, of the analysis of liquids, and 

 even in that of those substances which appear homogeneous 

 to the naked eye, it is quite indispensable to have recourse 

 to optical instruments, that we may ascertain if there be 

 globules in the fluid, and several distinct substances in the 

 solids. If globules are present, they must be studied as bodies 

 independent of the fluid in which they are discovered ; and if 

 distinct parts are found in a solid, they must, if possible, be se- 

 parated mechanically ; and when this is not practicable, we 

 must have recourse to the simplest reagents, such as water, 

 alcohol, ether, &c. Let us dwell for a moment on the mode 

 in which the chemist should examine globules. 



If, with the help of the microscope, we ascertain the form 

 of the globules, and traits of an organic structure, if ex- 

 isting, or any alliances of a physical kind which they 

 may possess, either among themselves or with another sub- 

 stance which is not globular, then these globules, as matter, 

 entering within the domain of chemistry, ought to be studied 



