TENDENCY TO CALCULOUS DISEASES. 
79 
Of phosphate of lime , and the mixed phosphates. 
During my analysis of the Norwich collection, I was accidentally led to 
suspect that carbonate of lime, though very unusual in urinary calculi in a 
separate and distinct form, was not an unfrequent concomitant of phosphate 
of lime. A particular examination of the collection, with a view to this special 
point, convinced me that such was the case. The existence of carbonate of 
lime was evinced by effervescence, on submitting a portion of the powdered 
calculus, to the action of dilute muriatic acid, in a small tube, after boiling it 
in distilled water, to extricate the atmospheric air involved in it. The gas 
evolved, was readily absorbed by pure potash over water ; while pure ammonia 
deposited the phosphate of lime, leaving a portion of fluid, from which lime 
was thrown down by oxalate of ammonia. — The same circumstance, likewise, 
happened, when the muriatic solution was evaporated to dryness, and the dried 
portion submitted to distilled water ; the muriate of lime, formed by the solu- 
tion of the carbonate being dissolved, and the lime precipitated in the form of 
oxalate, by oxalate of ammonia. Carbonate of lime, I have likewise seen in the 
mixed phosphates, and so extensively, as to induce me to think it probable, that 
phosphate of lime is seldom or never found in urinary concretions, either sepa- 
rately, or in combination with the triple phosphate, uncombined with carbo- 
nate. This circumstance seems to be the less unlikely, when it is considered, 
that carbonic acid gas has been found to exist in a pure state in urine, and 
separable by the mere aid of diminished atmospheric pressure. This being the 
case, it may fairly be expected to unite with some portion of lime during the 
evolution of the latter, instead of suffering the whole of it to be employed in 
forming oxalate, or phosphate of lime. 
I am happy in having had the kind assistance of Dr. Prout, and of Mr. Fa- 
raday of the Royal Institution, in ascertaining the existence of carbonate of 
lime, in some of the specimens of calculi in which that substance is not usually 
looked for. To Dr. Prout the circumstance was not unexpected ; for he has 
long considered the existence of carbonate, with phosphate of lime in human 
concretions, exceedingly likely, though he had not put his ideas to the test of 
experiment. — An important confirmation of these observations I have likewise 
met with, in a paper by the distinguished Spanish chemist Proust, who states. 
