.si8 Mr, W. Brande's Additional Observations 



ammoniaco-magnesian phosphate with phosphate of lime ; he 

 was directed to abstain from magnesia and alkalies, and to 

 adopt a plan of treatment which it is the object of the second 

 section of this paper more particularly to explain. 



The foregoing is a well marked case of uric gravel with a 

 strong tendency to form calculi, materially relieved by the 

 use of alkaline remedies : it illustrates their usual effects when 

 carelessly persevered in, and shews the advantage with which 

 magnesia may in such instances be employed : it also exhibits 

 the effect of magnesia and the alkalies, in producing the de- 

 posit of white sand (or phosphates) in the urine, when the 

 red sand (or uric acid) has been removed. 



The cases which follow are selected, from among others, 

 to explain the best mode of preventing the formation of white 

 sand, and to shew the most effectual treatment where it is a 

 natural deposit in the urine, or where it has been induced by 

 the incautious exhibition of alkaline medicines. 



Section II. 



The white sand so frequently voided by persons labour- 

 ing under calculous complaints, was first analyzed by Dr. 

 WoLLASTON,* who found it composed of ammoniaco-mag- 

 nesian phosphate, either alone or mixed with variable pro- 

 portions of phosphate of lime. The use of acid medicines in 

 these cases was also first suggested by the same able chemist, 

 but although his valuable observations have been before tlie 

 public for nearly fifteen years, I am not aware that any 



• Phil. Trans. 1797. 



