MICROSCOPICAL DIAGNOSIS. 57 



Phosphate of lime is preserved in the naphtha and creasote 

 fluid. The crystals of the triple phosphate are preserved the 

 best in water to which a little chloride of ammonium has been 

 added. Cystine is preserved either in glycerine jelly or in the 

 naphtha and creasote solution. 



The urates and uric acid are preserved in the naphtha and 

 creasote solution also. Crystals of uric acid show nicely when 

 mounted in Canada balsam. To mount them in balsam, they 

 must first be thoroughly washed with distilled water and then 

 carefully dried. They are dried the best under a bell jar over 

 sulphuric acid. When dry, a drop of oil of turpentine is ad- 

 ded, and this is allowed to nearly evaporate when a drop of 

 Canada balsam is added and the slide gently warmed. are 

 must be exercised here that the heat be slight, otherwise the 

 crystals will be cracked in every direction. These crystals 

 show very nicely when mounted in this way. Crystals of ox- 

 alate of lime are best preserved in the naphtha and creasote 

 solution. 



Many of the crystals obtained from urine are preserved 

 the best in a dry state. Such are urea, nitrate of urea, ox- 

 alate of urea, creatine, creatinine, and many others. These 

 crystals are allowed to form upon the glass slide, when they 

 are thoroughly dried under a bell jar over sulphuric acid. A 

 shallow ring of. white zinc can be placed around the crystals 

 and the cover applied and hermetically sealed. In the great 

 majority of cases the crystals obtained from urine are not pre- 

 served in their mother liquid. 



