C *7° 1 
wife found great Quantities of Air in the human 
Calculus. 
I infufed two Drams of this Powder in two 
Ounces of boiling Water : This Infufion I filtred 
when cold. It was of a light brown Colour, and of 
a bitterifh faline Tafte. I calcined what remained of 
the Powder after the Infufion, till the Whole was 
black, and then it weighed a Dram aud three Grains. 
I made the following Trials with the Infufion. 
1. Mixed with Syrup of Violets, it became green.' 
2. With Oil of Tartar, the Colour was deeper 
without Ebullition, but the Mixture fent forth 
immediately a ffrong urinous Smell 5 the fame 
Smell arofe from rubbing fome of the Powder 
with Oil of Tartar. 
3. With Oil of Vitriol, and Spirit of Salt, it loft 
its Colour 5 but no Ebullition enfued. 
4. With a Solution of Sublimate in Water, the 
Mixture curdled, and let fall a light-grey Sedi- 
ment, leaving the Liquor quite tranfparent. 
5. With a Solution of Sublimate in Lime-Water, 
the Mixture grew turbid, and let fall a deep- 
yellow Sediment, in a much greater Quantity, 
and of a deeper Colour, than a Solution of Sub- 
limate and Lime-Water alone. 
From thefe Inquiries it appears, that the Stone is 
compounded of an Earth, Air, Mucus of the Sto- 
mach, and a faline Principle bearing great Refcm- 
blance to Sal Ammoniac . 
