204 On Gravelly and Calculous Cuncretlons. 



3. Phosphate of lime. 



4. Aninioniaco-niagnesian .phosphate. 



5. Oxalate of lime. 

 G. Silica. 



7- Animal matter. 

 From the prevalence of any of these ingredients, or their 

 relative proportions, he divides thcni into four genera; and 

 these again into twelve species: for an account of wliicli 

 I must refer to the tenth volume of tlie Connoissanccs Clii- 

 miques, and the Memoirs of the National Institute; not 

 proposing to go into their chemical properties I'urther than 

 may be necessary to my present inquiry ; namelv, of how 

 far acids may be conducive to the formation, or alkalescent 

 substances to the prevention, or even solution, of a large 

 proportion of gravelly and calculous concretions. We have 

 already remarked, that to the sagacity of J3oerhaave we are 

 indebted for the knowledge of gravelly matter being a con- 

 stituent part of urine kept in chemical solution in it ; and, 

 happily for mankind, only separable from it after being 

 some considerable time out of the body. After minutely 

 detailing the ingctiious means made use of by Boerhaave 

 to ascertain this important point, to which I beg leave 

 to refer, his commentator, V'^an Swietcn, goes on to ob- 

 serve : 



" Hoc calculi rudimenta adsunt etiani in urina hominum 

 sanissimorum ; qua?., si una cum urina secernuntur, antc- 

 quam ab urina secesserint, et concrescere inceperint, nuUo 

 niodo sanitatcm Itcdent. Cum autem observatum fuerit, 

 illam separationem rudimentorum calculi citius fieri in qui- 

 busdam hominibus, tardius in aliis, patet, illos magis cal- 

 culo obnoxios viverc, in quibus citius ha;c scparatio arenu- 

 larum obtinet. An quandoque ilia separatio contingit jam 

 in renibus, et in vesica, antequam urina e.xpellatur de cor- 

 pore ? Certe videtur. Vidi saepius, una cum urina excretum 

 sabulum ncphriticum expulsum fuisse, statinique, calente 

 adhuc et fumante urina, in fundo matulae subsedisse. Con- 

 tigitaliquoties, inventam fuisse, in linteis sanorum infantum 

 urina madidis, copiam sabuli nephritici, satis duri, quod 

 videtur una cum urina excretum fuisse. Cum enim magna 

 cura habcretur, ne hi infantes, (illustri genere nati,) diutius 

 urina, vel aliis sordibus, conspurcati manerent, et urina 

 statim per lintea penetret, vix videtur possibile fuisse, ut in 

 urina jam emissa hoc sabulum productum fuerit, intra imam 

 alteramve horum." 



And again he adds : '' Hoc sabulum, in urina etiam sa- 

 nissima concrescens, vocari posset calculus nativus; a quo 

 nemo liber est ; at qui tunc tantum metuendus videtur, si 



cito 



