THE EARTHY AND ALKALINE PHOSPHATES. 343 



45 grains of magnesia produced no effect in two hours and three quarters ; in 

 five hours there was a marked increase ; in seven hours and a half a still greater 

 increase, which was very marked at the end of twelve hours, and possibly continued 

 for twenty-seven hours to influence the amount of earthy phosphates. 



30-8 grains of magnesia produced no increase in two hours and a quarter ; in four 

 hours and three quarters the increase was very evident ; and after eight hours and 

 three-quarters it was still very marked ; and after even twenty-six hours it still in- 

 creased the amount of earthy phosphates in the urine. 



These last experiments give the explanation of the rapid increase of phosphatic 

 calculi, and of the enormous quantities of earthy matter discharged, when magnesia 

 or lime-water have been taken in calculous affections. They show that these sub- 

 stances, having probably combined with different acids, pass off by the urine, and 

 when this latter is alkaline react on the phosphate of soda, and thus increase con- 

 siderably the amount of earthy phosphates in the deposit. 



The result of these experiments is, that the amount of earthy phosphates precipitable 

 by ammonia, depends chiefly on the amount of earthy matter taken into the body ; 

 and that the amount of alkaline phosphates is also most chiefly influenced by diet; 

 yet that there is an additional cause constantly acting in the state of health, namely 

 the production of phosphoric acid by the changes in the tissues of the body. And 

 as in disease some of these tissues may be more particularly engaged, so then may 

 the amount of alkaline phosphates point out the character, and declare the nature of 

 the structure which is the seat of the affection. 



On Alkalescence of the Urine from Jixed Alkali. 



The cases in which the urine is alkaline may be divided into two classes. In the 

 one the alkalescence arises from volatile alkali, and in the other from fixed alkali. 

 In the first it is caused by carbonate of ammonia, and in the second by carbonate of 

 soda, or potash, or alkaline phosphate of soda. Decomposition of urea is the origin 

 of the one, and disordered secretion of the other. 



Whenever alkalescence arises, the earthy phosphates, whatever their quantity, are 

 generally precipitated ; and hence the expression phosphatic diathesis, a term which 

 makes no distinction between the different kinds of alkalescence, nor between cases 

 in which the earthy phosphates, sometimes far below their average quantity, simply 

 appear in consequence of their insolubility in alkaline fluids, and cases in which a 

 vast excess of earthy or alkaline phosphates is being excreted. 



The object of the present paper is to point out the fact and the value of the distinc- 

 tion between the different kinds of alkalescence. 



M. Pelouze has shown how rapidly decomposing mucus effects the conversion of 

 urea into carbonate of ammonia. Irritation of the mucous membrane may give rise 

 to mucus which produces this change, and in consequence the blue colour will be 

 restored to reddened litmus paper if dipped into urine containing such mucus ; or if 



MDCCCXLV. 2 z 



