t 293 3 



LVI. An experimental Inquiry into the Nature of Gravel! ij 

 and Calculous Concretions in the Human Subject ; and 

 the Effects of Alkaline and Add Substances on them, 

 in and out of the Body. By Thomas Egan, M.D. 

 M.R.I.A. 



[Cctfitinued from p. 212.] 



X HESE facts being pretty \veH established and acknow- 

 ledged, it is time to inquire how far we mav account for 

 them j and whether experiments, instituted out of the body, 

 may not throw some Hght on this subject. Dr. Saunders, 

 in a letter to Dr. Percival, (Pcrcival's Essays, Medical and 

 Experimental, vol. iii.) on the subject of carbonic acid as 

 a solvent of calculous concretions, observes, '■ If a more 

 powerful and active sojvcnt than any hitherto known shall 

 be discovered, it is highly probable that such a discovery 

 can only be made by a rational and chemical inquiry into the 

 powers of different bodies of combining with the contents 

 of the urine, and preserving them in a fluid state out of the 

 body." Now, on the other hand, we may presume, that 

 whatever substances cause a separation or precipitation of 

 uric acid, in an aggregate state, from healthy urine, will 

 give rise to these disorders. For we are not to forget that 

 the uric acid, which forms so large a proportion of calcu- 

 lous concretions, and the entire of the gravelly, is a natural 

 secretion from the blood, performed by the functions of the 

 kidneys, and excicted by the urine, and can only be pre- 

 judicial by a previous morbid separation from it within the 

 body. With this necessary \ lew of the subject before us, 

 (for which we are, as already observed, indebted to Eocr- 

 haavc,) 1 resolved to trv, 1st, What might be the eflects of 

 acids of different kinds on liealtliy urine, as to their inliuence 

 in causing this «ame previous precipitation ; and, 2dly, that 

 of alkalmc substances in preventing if. And here it nnist 

 be observed, that to draw any satisfa<"lory conclusions fr'uu 

 experiments made with these substances out of the body, 

 we must suppose they reach the kidneys and blend with 

 the urine, still possessing their relative distinctive proper- 

 ties; and that this takes place, we have every reason to 

 presume. Doctors I'ercival and vSaunders, Mr. Bevvley, 

 and others, have ascertained the presence of carbonic acid, 

 in an uncomblncd state, in the urine of those who drank 

 .the niephitlc water for some days : an acid certainly foreign 

 'o its recent healthy state ; for, after repeated trials, by 

 healing it to nearly ebullition in oiin of rs'icsllev's air bot- 

 T 1 ties. 



