152 THE PHYSIOLOGY OF URIC ACID 



shower of crystals may often be prevented by Gee's 

 treatment, consisting of a large cupful of whey three 

 times a day. 



A simple apparatus for determining the amount 

 of total purin in the urine has been invented by 

 Walker Hall. It is readily used for chnical work. 

 The principle adopted is to precipitate the phos- 

 phates with magnesia mixture, then add ammoniacal 

 silver nitrate, leave standing for twenty-four hours, 

 and read the amount of the silver purin precipitate. 



CALCIUM OXALATE. 



It has Ijeen found very difficult to obtain reliable 

 estimates of oxalates in the urine. The method 

 commonly employed, introduced by Dunlop, is open 

 to serious objections from the chemical standpoint. 

 Working with O. C. M. Davis, the writer has used a 

 new and, theoretically, more reliable method, but 

 it is not claimed that the results are more than 

 approximate. There is still, therefore, some differ- 

 ence of opinion as to the metabolism of the oxalates, 

 but the following conclusions are becoming generally 

 accepted. 



In ordinary circumstances, the whole of the oxalate 

 in the urine is derived from articles of food. Milk, 

 meat, and bread contain scarcely any oxalate ; most 

 vegetables contain it, and rhubarb, strawberries, 

 and sorrel contain a relatively large quantity. I 

 have by taking much rhubarb induced an attack 

 of oxaluria sufficiently marked to cause a good deal 

 of smarting pain in the urethra from the sharpness 

 of the oxalate crystals. On a milk diet, oxalates 



