14 Observations on the Effects of 



hour after it had been taken into the stomach, and in less 

 than two hours the whole of the alkali had passed off. 



Experiment <2. On Soda, with excess of Carbonic Arid. 



The same quantity of soda, dissolved in eighi ounces of 

 water very highly impregnated with carhoi ic .:cid, was 

 taken under the same circumstances as in the former ex- 

 periment, and the urine was voided at nearly similar in«j 

 tcrvals. 



The separation of the phosphates was less distinct, and 

 less rapid. In two hours after the urine had been voided, 

 there was a small deposit, composed principally of phos- 

 phate of lime ; there was also a distinct pellicle on the sur- 

 face, consisting of the triple phosphate of ammonia and 

 magnesia. This appearance, produced by the escape of 

 the carbonic acid, which had before retained the ammonia-* 

 co-magnesian phosphate iti solution, and which now oc- 

 casions its deposition on the surface, is by no means un* 

 common, even in the urine of healthy persons : in the pre- 

 sent instance, it appears to prove, that carbonic acid passes 

 off from the stomach, by the kidneys ; for, after taking the 

 alkalies, in water very highly impregnated with it, the pel- 

 licle is uniformly produced, and is also much more abun-r 

 (lant and distinct than under any other circumstances 



In similar experiments with potash, the results were in 

 all cases as similar as could be expected in researches of 

 this nature. 



Experiment 3. On Magnesia, 



Magnesia was taken under circumstances similar to those 

 of the soda in the former experiment: in the quantity of 

 half a drachm, it produced no sensible effect upon the 

 urine during the whole day. When taken in the dose of 

 a drachm at nine o'clock in the morning, the urine voided 

 at twelve o'clock became slightly turbid : at three o'clock 

 the effect of the magnesia was at its maximum, and a di- 

 stinct separation of the phosphate* took place, partly in 

 the form of a film, which when examined was found to 

 be the triple phosphate of ammonia and magnesia, and 

 partly in the state of a white powder, consisting almost 

 entirely of the triple phosphate and phosphate of lime. 



The effect of large doses of magnesia, in producing a 

 white sediment in the urine, is very commonly known, and 

 has been erroneously attributed to the magnesia passing 

 off by the kidneys. 



These experiments show that magnesia, even in very 



large 



