ITS INCIDENTAL CONSTITUENTS. 415 



mentation, or as sparkling wine, which may probably be owing to 

 the circumstance noticed by Couerbe,* that when the pressure is 

 removed from Seltzer water, it only retains one volume of gas, and 

 probably loses a large portion of its acid by eructation after it has 

 entered the stomach ; whilst, on the contrary, champagne gives off 

 only one half volume of its four volumes of condensed carbonic 

 acid. It must be observed, however, that this transition of the 

 carbonic acid from those highly carbonated drinks, or from alka- 

 line bicarbonates, into the mass of the blood and the urine, is only 

 very distinctly manifested when the substances in question are 

 taken on an empty stomach. Buchheim has proved this to be the 

 case, by repeated experiments on himself. A development of gas 

 necessarily takes place as soon as food is introduced into the 

 stomach, as we may readily comprehend from known physical and 

 chemical grounds, and which is plainly manifested by eructations, 

 and frequently also by flatulence, even enabling us in some cases 

 to determine by percussion of the abdomen in what part the fluid 

 containing the carbonic acid is in contact with the intestinal 

 contents. 



The alkaline carbonates obviously reappear, from what has been 

 already stated, in the urine, although a portion of them must have 

 been saturated by the acid juices of the stomach and intestines. 

 It would be interesting to determine how much alkaline carbonate 

 is necessary in order to induce the secretion of a neutral or faintly 

 alkaline urine in man under definite conditions. Buchheim, who 

 for some time instituted experiments of this nature on himself, 

 found that even with reference to food and general dietetic relations, 

 the quantity of alkali necessary for this purpose was extremely vari- 

 able; this, however, is easily explained, when we consider how 

 many causes there are which, in a greater or less degree, influence 

 the acidity of the urine, and which are altogether beyond the con- 

 trol of the experimenter. 



Iodine combines very rapidly with alkalies in the animal body, 

 and then appears as iodide of potassium in the urine. 



Soluble baryta salts, although they are so easily decomposed by 

 sulphates, phosphates, and carbonates, yet, if given in sufficient 

 doses, reappear, according to Wohler, in the urine. 



Ferridcyanide of potassium reappears in the urine as ferrocya- 

 nide of potassium. 



Sulphocyanide of potassium, even when administered in small 

 doses, may very soon be detected in the urine. 

 * JourD. de Pharm. T. 26, p. 221. 



