322 PHYSIOLOGICAL CHEMISTRY.' 



and senna cause the urine to give a similar reaction. Reactions due 

 to such substances may be differentiated from the true blood reac- 

 tion by the fact that both the precipitate and the pigment of the 

 former reaction disappear when treated with acetic acid, whereas if 

 the color is due to hsematin the acid will only dissolve the precipitate 

 of phosphates and leave the pigment undissolved. 



2. Teichmann's Haemin Test. Place a small drop of the sus- 

 pected urine or a small amount of the moist sediment on a micro- 

 scopic slide, add a minute grain of sodium chloride and carefully 

 evaporate to dryness over a low flame. Put a cover glass in place, 

 run underneath it a drop of glacial acetic acid and warm gently 

 until the formation of gas bubbles is observed. Cool the prepara- 

 tion, examine under the microscope and compare the form of the 

 crystals with those reproduced in Figs. 58 and 59, page 198. (See 

 Atkinson and Kendall's modification, p. 197.) 



3. Heller-Teichmann Reaction. Produce the pigmented pre- 

 cipitate according to directions given in Heller's test on p. 321. If 

 there is a copious precipitate of phosphates and but little pigment 

 the phosphates may be dissolved by treatment with acetic acid and 

 the residue used in the formation of the haemin crystals according 

 to directions in Experiment 2, above. 



4. v. Zeynek and Nencki's Haemin Test. To 10 c.c. of the 

 urine under examination add acetone until no more precipitate 

 forms. Filter off the precipitate and extract it with 10 c.c. of 

 acetone rendered acid with 2-3 drops of hydrochloric acid. Place 

 a drop of the resulting colored extract on a slide, immediately place 

 a cover glass in position and examine under the microscope. Com- 

 pare the form of the crystals with those shown in Figs. 58 and 59, 

 page 198. Hsemin crystals produced by this manipulation are 

 sometimes very minute, thus rendering it difficult to determine the 

 exact form of the crystal. 



5. Schalfijew's Haemin Test. Place 20 c.c. of glacial acetic 

 acid in a small beaker and heat to 80 C. Add 5 c.c. of the urine 

 under examination, raise the temperature to 80 C. and stand the 

 mixture aside to cool. Examine the crystals under the microscope 

 and compare them with those shown in Figs. 58 and 59, page 198. 



6. Guaiac Test. Place 5 c.c. of urine in a test-tube and by 

 means of a pipette introduce a freshly prepared alcoholic solution 

 of guaiac (strength about i :6o) into the fluid until a turbidity re- 

 sults then add old turpentine or hydrogen peroxide, drop by drop, 

 until a blue color is obtained. This is a very delicate test when 



