The only C., and the percentage of albumin de termined by weighing.
For clinical use several approximate methods have been invented.
Esbach employs an albuminometer,— i.e., a graduated glass tube; this tube is filled to one mark (U) with the urine and then to the mark R with the test solution consisting of picric acid, 10 grammes; citric acid, 20 grammes; water, 1 litre. The tube is then closed with a rubber stopper and the contents can tiously mixed. The mixture is allowed ' to stand undisturbed for twenty-four hours and the quantity of precipitated albumin then read off. The reading in dicates in grammes the amount of albu min per litre.
Christensen recommends another method: the albumin contained in five cubic centimetres of urine is precipitated by ten cubic centimetres of a watery solution of tannic acid (1 per cent.). The albumin having been precipitated, 1 cubic centimetre of an ordinary gum arabic mucilage is added, the volume brought up to 50 cubic centimetres with water, and the whole converted to an emulsion by agitation. Upon a piece of white paper, ruled with black lines 0.5 millimetre wide and at equal intervals, is placed a cylindrical glass measuring four centimetres in diameter. This is half-filled with water, and as much of the emulsion run in as possible without obscuring the black and white lines be neath the vessel. From the number of cubic centimetres required, reference to a table of calculations arranged by Chris tensen furnishes the proportion of albu min present in the emulsion. When the urine is alkaline it should be faintly acidi fied with acetic acid before the precipita tion of albumin. This test can be made as well by daylight as by the light of a good lamp, and requires only ten or fifteen minutes; but is not applicable to urine containing a small amount of albumin, the variations amounting to two-thousandths.
The polariscope is sometimes employed to estimate the quantity of albumin, but this test is not very reliable. It is true
that albumin is but this is also the case with normal urine. and sometimes the color of the urine is too dark to allow the use of the polariscope. — By the tests above mentioned, as well qualitative as quan titative, the different coagulable proteids contained in the urine are precipitated; it is rarely of any use to differentiate them one from another.
Pure globulinuria without the simul taneous presence of serum-albumin does not occur. In order to precipitate the globulin alone the urine is rendered alkaline with solution of ammonia, after some time filtered, and the filtrate mixed with an equal volume of a saturated solution of sulphate of ammonia. If globulin be present a flaky precipitate will appear.
[The same result can be obtained by using a solution of sulphate of magnesia, which does not precipitate the other proteids of urine. or by diluting the urine until it reaches a specific gravity of 1002 and leading a slow current of carbonic acid through it for two or four hours. After twenty-four to twenty-eight hours the globulin will be precipitated. LEvi sox.] The hemialbumo.se, or propepton, which seems to be a mixture of different albumoses, may be revealed by saturation of the urine with chloride of soda and addition of acetic acid. When hemiallm mose is present a precipitate will appear dissolves by the addition of much acetic acid and heating, but reappears when the liquid cools again.
Nucleo-albumin, in small quantity, seems always to be contained in the urine. It is revealed by the addition of an excess of acetic acid to the urine, which becomes turbid, indicating the presence of a larger quantity of nucleo albumin. When the urine is very much concentrated it should be diluted with water before adding the acetic acid, as the nucleo-albumin is held in solution by the salts of the urine.