On Gravelly and Calculous Concretions. ■ 30.5 



depositing, sometimes from the bladder itself, but gene- 

 rally before it has entirely parted with its natural tempera- 

 ture, a very large proportion of a reddish brickdu^t-like 

 sediment (a welcome harbinger to gouty patients), cradii- 

 ally declining, and keeping pace with 'the alleviation of 

 symptoms, and the progrc:-sive return of the urine to its 

 natural degree of acidity. This sediment, Scheele, Berg- 

 nian, and Foiucroy, consider of the uric acid kind : and so 

 It (but in part only) undoubtedly is, being in a smaller pro- 

 portion than they were aware of! For, considering that the 

 enormous quantity, rendered in a few days, was incompati- 

 ble w-ith the known minute proportion of this acid matter 

 m urine, I was determined to make the following experi- 

 ment : — To a considerable quantity of it, desiccated and 

 well edulcorated with distilled water, were added three 

 ounces of a weak alka'me lixivium ; which, after a few hours 

 .digestion, coippletely discoloured it, acquired a ffolden yel- 

 low colour, a Swedish tasie, and, on the addition of aVew 

 drops of dilute marine acid, precipitated a copious sediment 

 of whitish, minute, needle-shaped crystals, of a silkv ap- 

 pearance. 



To this precipitate, well edulcorated, was added, by de- 

 grees, about one ounce of weak nitrous acid, which acted 

 on It with effervescence, and nearly took up the whole. 

 This solution, being set to evaporate, began to redden the 

 fingers, and other animal matters; no doubt, therefore, 

 could subsist as to its nature. 1 o the remainder, which 

 seemed very little diminished, and only deprived of colour, 

 \\cre added tvv'o ounces of dilute marine acid, which, after 

 «)me lime in digestion, nearly dissolved the whole ; and 

 finding this acid solution precipi'tate with lime water, oxalate 

 of ammonia, and fixed alkali, it must have been phosphate 

 of lime. This forms, then, by far the largest proportion 

 of the gouty sediment, which' is coloured by the precipi- 

 tated uric acid. Such also is the result of Crookshank'.s 

 experiments ; and so we should expect to find it, as I shall 

 endeavour to point out, 0!i a future occasion. 



Let us now conquer how far these analytical results may 

 be confirmed in the synthetic way, having resolved that 

 expeririient, as far as applicable, should ff)rm the basis of 

 any opinions offered in this essay. The phosphoric, being 

 the native acid, prevalent in urine, it was interestino- to de- 

 termine, whether, by the artificial super-iuidition of it, so 

 at. to bring this f^uid to the standard of the gouty, we might 

 not produce effects somewhat analogous to wfiat occur 

 there. 



Vol. 23. No. 92. Jan. 16U6. U Eighteen 



