TRANSPORTABLE REAGENTS FOR AL BUMIN.—Hoffmann and Aazette employ strips of test-paper previously placed in a solution of the double iodide of potas sium and mercury until saturated, then removed and dried. The urine which is to be tested should be clear and rendered acid by means of a few drops of acetic acid. If there be albumin present, upon immersion of a slip of paper in the urine a distinct precipitate will appear.
Pavy recommends test-pellets contain ing ferrocyanide of soda and picric acid; when albuminous urine is well shaken with a parcel of the pellet, albumin will be precipitated. The relative delicacy of the tests most frequently employed is graphically represented by Unger-Vetle sen, in the diagram shown on the oppo site page. The longest columns indicate the most delicate tests.
Sulphosalicylic acid, a white crystal line substance produced by heating sali cylic acid with concentrated sulphuric acid, precipitates all proteid substances. It shows traces of albumin in a dilution of 1 to 50,000. This reagent was first discovered by Reoch, then by MacWill iam, who employs sulphosalicylic acid in the form of a saturated solution. Per sonally employed by adding some of the crystals to a small quantity of filtered urine contained in a test-tube. The tube is then shaken. If albumin is present, a white homogeneous precipitate appears instantly. The urine should be acid. If the urine is alkaline it effervesces after the sulphosalicylic acid is added. If albumin is presented in the smallest traces, a cloudiness appears. When nitric or acetic acid is used far tests, small traces of albumin give rise to stringy, multiform particles suspended in a clear menstruum, the interpretation of which often gives rise to doubt. Sulphosalicylic acid gives a uniform opalescence which is unmistakable. Richard Stein (Med. Record, Jan. 16, '97).
Fifty samples of urine investigated each of which, from character of sedi ment, was judged to contain albumin. Those urines were selected in which small traces only of albumin were assumed to be present. With Millard's test, reaction was obtained in forty-eight of the fifty specimens. Two samples showed no re
action with any test; so that with Mil lard's test comparative efficiency would be 100 per cent. Roberts's test showed SO per cent.; ferrocyanide, 66 per cent.; nitric acid, 60 per cent.; heat, 52 per cent. Dilutions up to 1 in 320 showed positive results with all the reagents. When strength was reduced to 1 in 040, only Millard's test showed re action, and the limit to the reaction was about. 1 in 1280. Unless pepton is pres ent in large quantities, it is not precipi tated by action of Millard's reagent. J.
W. Garratt (N. V. Med. Jour., July 16, '9S).
A glass pipette is used and the urine allowed to run up the tube one or two inches. The index finger is then placed on the top and the urine washed and dried off the outside of the tube. It is then inserted into nitric acid and the index finger partially removed to allow the acid to flow up the tube. The presence of albumin al ways causes a white ring to form at the line of contact. Globulin, albu moses, and peptones may also cause a small ring at the zone of contact, but method which gives fully reliable re sults is the gravimetric method. One hundred cubic centimetres of urine are cautiously heated to the boiling-point; if precipitation does not take place a few drops of a weak solution of acetic acid are added; the liquid is now brought on a weighed filter and the precipitate repeatedly washed with hot water. When the water has been removed from the filter by strong alcohol, the filter is dried by a temperature of 120° to 130° they are seldom present. If suspected they may be tested for by boiling the urine. A cloud appears just before the boiling-point is reached, but disappears when boiling occurs. Crates may cause a similar ring. Similar experiments have been tried with twelve other re agents which have been recommended for detecting albumin in urine, but the results were never so satisfactory as when nitric acid alone was used. T.. N. Boston (New I ork Med. Jour., May 24, 1902).