PROTEINS 



103 



Use of the Albumoscope.Thh instrument is intended to facilitate the making of 

 "ring" tests such as HeUer's and Roberts'. In making a test about 5 c.c. of the 

 solution under examination is first introduced into the apparatus through the larger 

 arm and the reagent used in the particular test is then introduced through the capil- 

 lary arm and allowed to flow down underneath the solution under examination. 

 If a reasonable amount of care is taken there is no possibility of mixing the two solu- 

 tions and a definitely defined white "ring" is easily obtained at the zone of contact. 



5. Nitric Acid. MgSO 4 Test (Roberts). Place 5 c.c. of Roberts' reagent 1 in 

 a test-tube, incline the tube, and by means of a pipette allow the albumin solu- 

 tion to flow slowly down the side. The liquids should stratify with the formation 

 of a white zone of precipitated albumin at the point of juncture. This test is a 

 modification of Heller's ring test and is rather more satisfactory. The albumo- 

 scope may also be used in making this test (see Fig. 135, page 440). 



6. Spiegler's Ring Test. Place 5 c.c. of Spiegler's reagent 2 in a test-tube, in- 

 cline the tube, and by means of a pipette allow 5 c.c. of albumin solution, acidified 

 with acetic acid, to flow slowly down the side. A white zone will form at the point 

 of contact. This is an exceedingly delicate test, in fact too delicate for ordinary 

 clinical purposes, since it serves to detect albumin when present in the merest trace 

 (i : 250,000). This test is further discussed on page 424. 



7. Tanret's Test. To 5 c.c. of albumin solution in a test-tube add Tanret's 

 reagent, 3 drop by drop, until a turbidity or precipitate forms. This is an exceed- 

 ingly delicate test. Sometimes the albumin solution is stratified upon the reagent 

 as in Heller's or Roberts' ring tests. In urine examination it is claimed by Repiton 

 that the presence of urates lowers the delicacy of the test. Tanret claims that the 

 removal of urates is not necessary inasmuch as the urate precipitate will disappear 

 on warming and the albumin precipitate will not. He says, however, that mucin 

 interferes with the delicacy of his test and should be removed by acidification with 

 acetic acid and filtration before testing for albumin. 



8. Sodium Chloride and Acetic Acid Test. Mix 2 volumes of albumin solu- 

 tion and i volume of a saturated solution of sodium chloride in a test-tube, acidify 

 with acetic acid, and heat to boiling. The production of a cloudiness or the 

 formation of a precipitate indicates the presence of albumin. 



9. Acetic Acid and Potassium Ferrocyanide Test. To 5 c.c. of dilute egg 

 albumin solution in a test-tube add 5-10 drops of acetic acid. Mix well and 

 add potassium ferrocyanide, drop by drop, until a precipitate forms. This test 

 is very delicate. 



Schmiedl claims that a precipitate of Fe(Cn) 6 K 2 Zn or Fe(Cn) 6 - 

 Zn 2 , is formed when solutions containing zinc are subjected to this test, 

 and that this precipitate resembles the precipitate secured with protein 



1 Roberts' reagent is composed of i volume of concentrated HNO 3 and 5 volumes of a 

 saturated solution of MgSO 4 . 



2 Spiegler's reagent has the following composition: 



Tartaric acid 20 grams. 



Mercuric chloride . . . . 4o grams. 



Sodium chloride 5 grams. 



Glycerol 100 grams. 



Distilled water ioo grams. t 



9 Tanret's reagent is prepared as follows : Dissolve 1.35 grams of mercuric chloride in 25 

 c.c. of water, add to this solution 3.32 grams of potassium iodide dissolved in 25 c.c. of 

 water, then make the total solution up to 60 c.c. with water and add 20 c.c. of glacial acetic 

 acid to the combined solutions. 



