THE EARTHY AND ALKALINE PHOSPHATES. 345 



stantly seen about three hours after breakfast, and very rarely at other times. In 

 others the alkalescence of the urine is frequently observed, but the deposit is rare ; 

 whilst in others the deposit by heat from acid urine is very frequently to be found ; 

 and alkalescence is seldom to be detected by test-paper in the water secreted from 

 two to four hours after food, and these three states often alternately occur in the 

 same case. 



Dr. Andrews of Belfast stated to me, that having observed a case otherwise in 

 perfect health, in which the urine was almost invariably alkaline about two hours 

 after breakfast, so much so as frequently to be loaded with a deposition of phosphates 

 whilst still in the bladder, he was led to observe the urine of about fifteen students 

 in good health immediately after it was voided about noon. He found it to be alka- 

 line in about two-thirds of the cases. Whether this tendency to alkalescent urine 

 may, as Dr. Andrews thinks, be connected with the immunity enjoyed by the inha- 

 bitants of his district from calculous affections, or whether alkalescence at this period 

 of the day is far more general everywhere than has been supposed, future observations 

 must determine. 



At the present time I know five physicians in whom the above phenomena at this 

 period of the day are more or less frequently visible in a greater or lesser degree ; 

 and in London this alkalescence will be found in those who are considered generally 

 healthy much oftener than is imagined. 



Supposing that acid phosphate of soda was the cause of the acid reaction of healthy 

 urine, it was thought that some explanation of the deposit on boiling might be gained 

 by observing the behaviour of phosphate of lime and phosphate of magnesia with 

 phosphate and biphosphate of soda. Pure solutions of these salts and of chloride of 

 calcium, and sulphate of magnesia were used, and the following results obtained. 

 The deposits were examined with a magnifying power of 320 times. 



Chloride of calcium gave no immediate precipitate with a strong solution of acid 

 phosphate of soda. If left to stand many hours, a crystalline precipitate formed 

 (fig. 3). When boiled no cloudiness was observed, if the quantity of phosphate of 

 lime present was small ; but if much was in solution, a crystalline precipitate fell on 

 boiling; and when cold, if filtered and again boiled, a very small crystalline precipi- 

 tate was occasioned, which did not entirely redissolve on cooling. 



When a solution of biphosphate of soda is mixed with chloride of calcium, an 

 immediate precipitate is caused by a drop or two of any alkali, and this is crystalline 

 (fig. 3), or granular (fig. 2), or these mixed according to the quantity of alkali added, 

 that is, according as much or little of the acidity of the solution is removed. 



If this precipitate was separated by filtration and the clear liquid boiled, a deposit 

 fell which was at first gelatinous (fig. 2), the fluid becoming more acid to test-paper. 

 The precipitate, if the solution was very acid, changed into the crystalline form 

 (fig. 3), and partly dissolved on cooling. 



If chloride of calcium was added to common phosphate of soda, a plentiful granular 



2 z 2 



