d. Albumen and fibrin are discovered by their solubility in diluted alkalies and in acetic acid. Neutralization causes a flocculent preci pitate soluble in excess of acetic acid or of the alkalies ; the acetic solution gives a precipitate on adding ferrocyanide of potassium. Before the blowpipe they swell up, leaving a bulky coal which burns with difficulty to a stnall white or yellowish ash ; they always contain saline matter. Albumen and fibrin, in com mon with all the compounds of protein, are further characterized by dissolving slowly in the concentrated acids; with sulphuric acid a crimson liquid is obtained, with nitric a yellow solution attended with effervescence during the action, and with hydrochloric acid a character istic violet-coloured liquid is procured.
e. The gelatinous tissues may be shewn to be such by continued boiling in water for tsventy four or forty-eight hours; the liquid, if not too dilute, has then the property of gelatinizing on cooling; with infusion of galls it should pro duce an abundant flocculent buff-coloured pre ci pitate.
j: Sometimes we meet with concretions formed principally of hairs; their texture and appear ance generally betray their composition. Be fore the blowpipe they are dissipated with the well-known smell of burnt feathers. Solution of potash dissolves them slowly, and the liquid then gives the reactions furnished by alkaline solutions of albumen.
g. Earthy phosphates.—Phosphate of lime rarely occurs alone, either as a sediment or cal culus; though in combination with others it is one of the most usual constituents of morbid concretions. Before the blowpipe, unless mixed with animal matters, it undergoes little change; usually a transient blackening appears from the charring of a little organic matter always pre sent ; by continuing the heat it becomes white. Nitric acid dissolves it readily, and phosphoric acid may be shewn by adding acetate of lead as directed when speaking of the detection of phosphoric acid. Ammonia in excess added to the acid solution causes a bulky gelatinous precipitate of bone earth ; on redissolving in acetic acid, and adding oxalate of ammonia, we obtain abundance of oxalate of lime.
Phosphate of ammonia and magnesia, or, as it is frequently termed, triple phosphate, is a common constituent of calculi and of white sand; when in the form of a sediment it ge nerally occurs in hemihedral six-sided prisms; heated before the blowpipe it emits ammonia, agglutinates, but is almost infusible; the addi tion of a fourth or a sixth of its bulk of phos phate of lime, as a shaving of bone or ivory, causes its immediate fusion to a white enamel like bead. It is soluble in acids, and ammo nia causes a crystalline precipitate of unchanged phosphate; phosphoric acid may be discovered by acetate of lead as before; oxalate of ammo nia causes no precipitate in the acetic solution unless lime be present.
Not unfrequently these two kinds are mixed, constituting what has been termed the fusible calculus, from its property of forming the ena mel-like bead before the blowpipe just men tioned. Heated with potash it evolves ammo nia. Phosphoric acid and lime may be shown as before. After the sepamtion of lime by oxalate of ammonia, supersaturation with ammonia throws down the crystalline phos phate of ammonia and magnesia.
h. Carbonate of fime.—These calculi be fore the blowpipe are converted into caustic lime, and then give a brown stain to turmeric paper. In dilute nitric or hydrochloric acid
they dissolve with effervescence. Lime may be shown in the solution by appropriate tests.
i. Oxalate of lime is now and then met with, forming a gravel crystallized in pale amber-coloured prisms, but usually in the form of larger concretions, from their tuber culated exterior termed mulberry calculi ; for the most part they have a dark brown or ma hogany colour. Ileated moderately before the blowpipe they yield a white ash, consisting principally of carbonate of lime, and dissolving with effervescence in acids. If the heat be greater, quicklime alone remains. It stains turmeric paper brown when moistened. Lime may be detected in the ash by the usual re agents. Oxalate of lime, when powdered, dis solves in nitric acid readily, more sparingly in hydrochloric acid. Ammonia throws it down unchanged from these solutions, and the preci pitate is insoluble in acetic acid.
The whole of the preceding experirnents may be made upon portions of matter not exceeding two grains, and most upon a quantity much smaller, especially if our examinations be aided by the microscope. Examinations of these matters are rarely quantitative; the small quantity of material procurable, and an unwill ingness to sacrifice morbid products of this description for the purposes of analysis, prevent us from possessing information so full and detailed upon the constituents of concretions in general as the numerous collections in exis tence would have led us to expect.
Calculi, especially urinary calculi, are far from presenting a uniform and homogeneous structure throughout, being in many if not in most cases composed of laminm differing mate rially in composition. It would be of little value to the pathologist to know the compo nents of all the different layers mingled indis criminately; the information he would derive as. to the process by which the stone was formed, and of the means by which tendencies to such formations might be counteracted, would be of the most confused and indefinite description, tending rather to mislead than to aid him in forming correct conclusions. Just so it is when chemical analysis is applied to organized tex tures in general without due regard to the struc ture and disposition of the proximate elements within them ; and hence the confused medley of substances obtained by subjecting them as a whole to the action of chemical agents. The texture', however, once known, and the action of our reagents upoii it being watched under the field of the microscope, we can at pleasure separate the different ingredients, and obtain, with comparatively little difficulty, results which are fixed and producible at will ; results which strictly belong to the domain of science, to whose enlargement and successful cultivation they then really contribute.
When soft tumours or malignant growths are submitted to our examination, one portion niust as usual be carefully desiccated, to determine the proportion of moisture ; and another, after being shred finely, macerated for some hours with water at a temperature not exceeding 100° F.; in this way the soluble albumen will be secrarated from the fibrous and other insoluble matters. The analysis must afterwards be pro ceeded with upon the principles already laid down, being first directed to the soluble ingre dients and then to the insoluble matters.