-On GraveUu and Calculous Concretions, 117 



Experiment XIV. 



Into a filtered solution of ten grains of salt ()f tartar, in 

 four ounces of distilled water, were introduced two fragments 

 of calculi, weighing seventy-four grains and a quarter. Tlie 

 mixture was set aside for forty-eight hours in a cool room; 

 temperature varyina; from 17 degrees at night, to 55 degrees 

 in the dav. After twelve hours it began to be coloured^ and 

 continued to be more so, until the temperature fell to 51 

 degrees, when a precipitation took place, and continued 

 during the night; so that it appeared to deposit at the tem- 

 perature of 4 7 degrees, what was taken up at degrees some- 

 what exceeding 51°. These fragments, on being taken out, 

 dried, and weighed, were found to have lost three grains and 

 three quarters ; the laminae disposed to crack, and the strata 

 to separate and crumble. 7'his weak lixiviunj, then, ex- 

 erted much energy, even in a very low temperature. 



F,.rperime7ii XV. 



A fragment of calculus, weighing seventeen grains thres 

 quarters, was inmiersed in a lixivium of similar strength ; 

 but now exposed to a temperature varying from 51 degrees 

 at night to about 95 degrees in the day. After forty-eight 

 hours, it was found to lose five grains and a half: a prodi- 

 gious quantity, when we consider the small surface pre- 

 sented by this fragment, weighing only seventeen grains 

 three quarters. The solution, upon cooling, became tuibid 

 as before, and precipitated a large proportion of ihe dissolved 

 uric acid. 



Experiment XVI. 



A fragment of calculus, weighing forty grains three quar- 

 ters, was immersed in four ounces of soda water for forty- 

 eight hours, and exposed to a temperature varying from 

 55 to about 100 degrees. Its loss amounted to one grain. 

 A repetition of this experiment aiforded nearly the same re- 

 Bult ; and demonstrates, that though the soda, in this super- 

 carbonated state, still exerts son)c energy on concretions of 

 the uric acid kind, yet it is but feeble ; and that these waters 

 appear more capable of preventing their formation than cU 

 H 3 ttcting 



