54 MICROSCOPICAL DIAGNOSIS. 



Cystine. Cystine is a very rare deposit. It forms a whitish 

 sediment which consists of colorless, transparent, six-sided plates 

 or prisms. These crystals are soluble in ammonia and upon 

 spontaneous evaporation of the ammonia the crystals are again 

 deposited unchanged in shape. As uric acid crystals are not 

 soluble in ammonia this test serves to differentiate between 

 the two. Cystine is insoluble in acetic acid, while the earthy 

 phosphates are soluble. The surfaces of the crystals of cystine 

 are frequently marked with lines of secondary crystallization. 



They are also often seen overlapping one another and 

 united by their sides. Cystine is insoluble in boiling water, 

 in carbonate of ammonia, in strong acetic acid and in weak 

 hydrochloric acid. It is soluble in the strong mineral acids, 

 in ammonia, potash, and oxalic acid. 



Carbonate of Lime. Carbonate of lime is occasionally found 

 in the crystalline state. It occurs in an amorphous form, and 

 is recognized by its effervescing when acetic acid is added to 

 it. Before applying this test the deposit should be washed with 

 distilled water to remove any soluble carbonate that might be 

 present. 



Blood-corpuscles. When blood-corpuscles are in the deposit 

 they give to it a red, or brownish-red, granular, or smoky ap- 

 pearance. The deposit should be examined for the character- 

 istic corpuscles. It should be remembered that the blood-cor- 

 puscles may become very much altered in their appearance by 

 remaining in the urine for a considerable time. If no blood- 

 corpuscles can be detected then the guaiacum test can be ap- 

 plied. A few drachms of the tincture of guaiacum are mixed 

 with an equal volume of oil of turpentine and well shaken 

 until an emulsion is formed. The urine is carefully added to 

 this mixture. As the urine comes in contact with the emul- 

 sion a precipitate is formed. The precipitate is at first white, 

 later it becomes yellow or green. If the urine contains any 

 blood, even slight traces of it, the 'precipitated resin will be 

 colored a more or less intense blue, many times an indigo-blue. 



TO TEST FOR SUGAR. 



The quantity of urine in diabetes, secreted during the twenty- 

 four hours varies from eight to fifteen or more pints. It usually 



