1848 Journal of Applied Microscopy 



ELEMENTARY MEDICAL MICRO-TECHNIQUE. 



For Physicians and Others Interested in the Microscope. 



Copyrighted. 



VI. URIC ACID. 



Uric acid is normally in urine in about -^^^ of 1 per cent. Abnormally it 

 may be present in varying quantities in the form of bright yellowish, red colored 

 crystals, rhombic in form and bunched together like a small pile of shingles. It 

 may also be present in unusual quantity in the form of urates. The quantitative 

 estimation of uric acid, free and as urates, is a little difficult, but should be done 

 in all cases where it is suspected in abnormal quantities, or when a very careful 

 examination of the urine is required. Proceed as follows : 250 c. c. of the 24 

 hours urine should be acidulated with acetic acid, boiled and filtered. 

 To 200 c. c. of this filtered urine add 10 c. c. of hydrochloric acid, C. P.; set 

 aside for 24 hours in a cool place. The urates will be decomposed into uric acid, 

 which without the free uric acid will crystallize on the .sides of the vessel. 

 Decant the urine, scrape the crystals loose, add water and filter. Be careful to 

 w^ash all of the crystals out of the vessel so that they may be caught on the filter 

 paper. Before filtering the filter paper should be heated to dry it thoroughly 

 and carefully weighed. After filtering dry the filter paper thoroughly with heat 

 and weigh again. The difference in the weighs will represent the amount of 

 uric acid in 200 c. c. of urine. In normal urine the difference in weight should 

 be about 85 milligrams, which would be the amount of uric acid in 200 c. c. If 

 1200 c. c. of urine be passed the uric acid should be six times 85 milligrams or 

 510 milligrams or .510 grams. 



A sensitive balance is necessary for the delicate weighing. 



Uric acid is increased in the following diseases: Fevers, leukaemia, acute 

 articular rheumatism, diseases of the spleen, whooping cough, chorea, etc. It is 

 decreased in chronic diseases of the spinal cord, chlorosis, anaemia, gout with 

 deposits, etc. 



CHLORIDES, PHOSPHATES AND SULPHATES. 



For estimating the quantity of chlorides, phosphates and sulphates present in 

 the urine, the centrifuge method is recommended. Either a reliable hand or 

 electrical centrifuge may be used. The results are arrived at quickly and accu- 

 rately. 



Chlorides. — The percentage tubes are to be filled to the 10 c. c. mark with 

 urine, add 15 drops of nitric acid to hold the phosphates in solution, add suffi- 

 cient nitrate of silver solution (composed of 5 grams nitrate of silver dissolved 

 in 40 c. c. of distilled water) to fill to the 15 c. c. mark. Close the tube with the 

 thumb and thoroughly mix. Put in the centrifuge and rotate at the rate of 1000 

 revolutions per minute for three minutes. The normal range of chlorides by 

 this test is 10 to 12 per cent, read directly from the tube. The divisions 1, 2, 3, 

 etc., are 10, 20 and 30 per cent., being ^, -^^ and y^^ of the 10 c. c. of 

 urine used for the test. Clinically it is only desirable to know whether the 



