416 Mr. T. Taylor's Observations on Urinary Calculi 



and in which the characters of urate of ammonia began to pass 

 into those of the phosphates, gave on analysis: 



Uric acid 9*1 



Phosphate of lime 1*5 



Phosphate of ammonia and magnesia 3*1 



Animal matter, ammonia, and loss ... 1*3 



15-0 

 The ash which is left when these calculi are burnt is almost 

 always alkaline and infusible: in three cases only were the 

 phosphates present in such proportions as to render it fusible. 

 By reference to the table it will be seen that urate of ammonia, 

 so far from being rare, as is generally stated, forms in the pre- 

 sent collection the most frequent primary deposit; as out of 

 82 calculi which have been divided, the proportion as to nuclei 

 is as follows: uric acid 18, urate of ammonia 41, oxalate of 

 lime 23 ; and in those which are homogeneous the proportion 

 of urate of ammonia though less is still very considerable. It 

 has been remarked by Dr. Prout, that this species of calculus 

 generally occurs in children, and the accuracy of this obser- 

 vation is fully borne out by the histories attached to these 

 calculi ; for although unfortunately they are not so perfect as 

 to enable me to institute a strict comparison of the relative 

 frequency of each variety at the different periods of age, yet 

 in the present case by far the greater number are expressly 

 stated to have been taken from persons under puberty. 



Phosphate of Lime. — Under this head are arranged some 

 small calculi from the prostate gland, and three large irregu- 

 lar concretions from the kidney ; two of these contained car- 

 bonate of lime and some urate of ammonia, the latter being 

 apparently in separate layers. In one a small quantity of the 

 phosphate of ammonia and magnesia was likewise present. 

 Whether the phosphate of lime in these calculi was primarily 

 secreted, or merely coated a nucleus of some other substance, 

 is uncertain, as on account of their figure it was not considered 

 advisable to divide them. The other specimen was examined 

 by Dr. Hue, and consisted of phosphate of lime with a large 

 quantity of animal matter. 



The term bone earth which is frequently applied to these 

 calculi is faulty, as it conveys the idea that the lime and phos- 

 phoric acid are in the same relative proportions as in the 

 earthy matter of bones ; whereas it has been shown by Dr. 

 Wollaston that the calculi from the prostate gland contain a 

 much larger proportion of acid, forming what is usually termed 

 the neutral phosphate, or more correctly speaking the diphos- 



