VOL. XVI.] PHILOSOPHICAL TRANSACTIONS. 317 



This stone sent from Bern for 13 drs. must either have been avoirdupois, or 

 else is wasted something, for he found it only to weigh in the air 12 dr. 36 gr. 

 in water 6 dr. 48 gr. The difference thereof is 5 dr. 48 gr. 



The proportion between this concrete and water proves to be as 756 to 348, 

 or as 2 and somewhat more than a 6th to 1 . 



This matter, compared with common chalk, was found specifically lighter, 

 bearing only the proportion to water of 521 to 290, considerably short of that 

 of 2 to 1 . Shells and testaceous bodies very nearly agree with this matter ; 

 which takes off the former opinion that this patient had perhaps devoured wall- 

 lime, and such like testaceous matter, from whence the stone might receive its 

 original : for this being broken into pieces, will not so easily cement again into 

 so compact a body as it was formed of, as we see in whiting, which is lighter 

 than chalk : Hence, this being vastly heavier than chalk, can scarcely be thought 

 a concretion of such a matter. 



Compared with petrified water, i.e. an icicle broken off a grotto, where the 

 petrifying spring furnished enough ; it came very near the gravity of our stone 

 and the usual weight of ordinary stones ; a piece that weighed 5 drams out of 

 the water, discovered its weight to bear the proportion of 403 to 184, or 756 

 to 345, to that of water. This anomalous substance being so near the weight 

 of our petrified water, would almost incline a man to l^elieve it real stone, and 

 the rather because we are informed the patient drank much water. The follow- 

 ing experiments also seem to prove that it is rather of the ordinary stony constitu- 

 tion, than of that which is proper to animal concretions. For instance, ordinary 

 vinegar was poured upon it, it presently wrought upon it with a hissing noise, as 

 it did on the petrified water when powdered. When spirit of vitriol was added, 

 it also dissolved it, but let it fall again, as aquafortis does tin when it has cor- 

 roded it ; which is agreeable to the relator's account. But it does not appear that 

 he used spirit of salt ; for this wrought upon it very vigorously, and presently 

 dissolved il, and kept it so without any precipitation. 



All these experiments distinguish this concrete from the ordinary animal 

 ones, as the stone in the bladder, kidney, the tophi, &c. for these will not be 

 dissolved, or in the least corroded by any of the mentioned acids : though spirit 

 of nitre be a general menstruum, which dissolves them all readily.* Dr. Slare 

 adds, that he failed in these trials to extract a volatile and fixed salt from it.'f- 



f The assertion that uninary and other animal calculi are not corroded or dissolved by any acid ex- 

 cept spirit of nitre (nitric acid) is erroneous. Many of them are soluble in the muriatic acid also. 



t In his " further trial" however be says that he distilled from it a liquor that looked and smelled 

 like spirit of hartshorn. 



