56 MICROSCOPICAL DIAGNOSIS. 



Fehling's solution should be kept in tightly corked bottles 

 and protected from the light. After having been kept for 

 some time this solution may deposit the suboxide when boiled 

 alone ; if this should be the case some fresh potash should be 

 added before testing the urine. 



THE PRESERVATION OF THE URINARY DEPOSITS. 



Urinary deposits may be preserved in Canada balsam, in 

 glycerine, in a i per cent, solution of carbolic acid, in equal 

 parts of glycerine and camphor water, in a solution of naphtha 

 and creasote and in various other media. 



The naphtha and creosote solution is of very general use 

 It is made as follows : 



Creasote, 3 drachms. 



Naphtha, - - 6 ounces. 

 Distilled water, 64 ounces. 



Prepared chalk, - a sufficient quantity. 



Mix the naphtha and creasote together, then add as much 

 of the chalk as may be necessary to make a thin, pulpy mass; 

 the water is now added gradually, the whole being well rubbed 

 together in a mortar. One or two small pieces of camphor are 

 added and the whole mixture is allowed to stand two or three 

 weeks in a closely covered vessel, being frequently stirred. At 

 the expiration of this time the clear fluid is poured off, and 

 filtered if necessary, and preserved in well corked bottles. 



When any urinary deposit is to be mounted in a fluid the 

 following method should be carried Out : The sediment is al- 

 lowed to settle in the test-tube, when as much as possible of 

 the urine is drawn off from it by a syphon. A quantity of the 

 preservative medium, equal in bulk to the contents of the tube, 

 is added to the sediment and the mixture well shaken ; this is 

 allowed to rest until the sediment settles to the bottom of the 

 tube again. The preservative fluid is now drawn off, as was 

 the urine, and a fresh quantity of the fluid added. By so do- 

 ing the deposit is thoroughly impregnated with the preservative 

 medium. 



Casts are preserved very well in the naphtha and creasote 

 solution. The very pale casts show much better by coloring 

 them with the carmine solution. 



