253 



vegetable matters do so. I will not mention the commu- 

 nication of so volatile a principle as odour, but will more 

 particularly dwell on that of colour. Rhubarb, turmerick, 

 madder, and many other substances, so completely impart 

 their colour to urine, that they would appear to be very 

 little altered. Nay, the juice of the beta vulgaris, a mild 

 esculent of the pentandrious class, so deeply reddens it, 

 as to cause it to be mistaken for bloody urine, of which 

 a late instance has occurred in my practice. 



As to alkaline substances, it has been at all times known, 

 that they communicate their properties to this excremen- 

 tious liquor. A perseverance in the use of the aqua kali 

 puri, of the shops, for a few days, even in small doses, 

 converts its acescent into the alkaline state; and we have 

 every reason to suppose, that the same takes place with 

 the carabonates, which are taken in so much larger quan- 

 tities. This seems confirmed, by experiments made in 

 London and Paris; and the alkalescent impregnation of the 

 urine was ascertained by the formation and precipitation 

 of the acidulous tartarite of potash, upon the addition of 

 the tartarous acid. Yet, from a good deal of experience 

 in these matters, I may aver, that, as to the carbonates, 

 the dose must be considerable, (which was the case in 

 London,) and continued for some time; having frequently 

 given two scruples of desiccated soda, (containing, accord- 

 ing to Mr. Kii'wan, 23,94 grs.) in the twenty-four hours, 

 for some days together, without any diminution of the 

 usual acidity of this liquor. 



VOL. X. K k For 



