256 



Having premised these observations, it is now time to 

 consider what effects acid substances are productive of, 

 when mixed, out of the body, with this very complicated 

 liquor. And here, to prevent repetition, I will observe, 

 that that generally used, was rendered fresh in the morn- 

 ing, in the quantity of from three to four ounces, (unless 

 otherwise specified;) being that most easily retained at one 

 time in the bladder. The quantity of acid extremely 

 small, for obvious reasons, and seldom increasing its aces- 

 cent properties (as ascertained by the usual tests) beyond 

 what frequently occurs, in the urine of those who use 

 acescent drinks, or are afflicted with gout or gravel. A 

 standard quantity was always laid by for comparison; and 

 the temperature from sixty to seventy-five degrees, being 

 in autumn, 1799. And to begin with the vegetable acids. 



EXPERIMENT I. 



To four ounces of the urine of an adult, was added one 

 drachm of common acetous acid, which (like every other 

 acid) caused no immediate change in it; but, in a very 

 short time, and before it cooled down to the temperature 

 of the atmosphere, some extremely minute shining spi- 

 culae, observable only by a lens, were seen floating in it: 

 these gradually increased in number and size, began to 

 reflect the light, and, from being perfectly transparent, 

 soon became coloured, to settle upon the usual cloud, or 

 nubecula, which now began to form, adhere to the sides 



of 



