[ 3°2 ] 
fufion, when cold and filtred, was of a light-brown 
Colour 5 whereas the Colour of the Water was not 
changed in either of the above-mentioned Infufions ; 
neither did any Ebullition enfue upon the Mixture of 
them with Oil of Tartar, Vitriol, <&c. 
I try'd to diffolve thefe Stones, by digefting fmall 
Pieces of them in the ftrongeft acid and alkaline 
Metiftrua , viz. Spirit of Salt, Sulphur, Oil of 
Vitriol, Aqua fortis , and capital Soap-Lees, fyc. 
and at the fame time try ’d the Effedts of thofe 
Menfirua on feveral Stones, which were given me 
by fome of my Patients, who voided them. They 
were foftened by fome of them, but not totally di£ 
folved by any, except the Oil of Vitriol and Aqua 
fortis : Nor di4 the Aqua fortis caufe any Ebullition 
in diffolving them, as it did in the Solution of the 
Calculus humanuSy which was attended with a brisk 
Ebullition, and hilling Noife, arifing from the Erup- 
tion of the Air Bubbles from it: Which confirms 
what I obferv’d above, that thefe Stones contain but 
a very fmall Quantity of Air, and that their faline 
and oily Particles are fo clofely combined with Earth, 
as not to be cxtra&ed without a flrong Fire. 
Havant , Nov. 27. 
1746. 
Explication 
