414 URINE. 



in addition to solubility, and the incapacity for entering into inso- 

 luble combinations, they should possess another character, namely, 

 that of being already perfectly oxidised, or that of having no ten- 

 dency t > oxidation and decomposition generally. Thus, for instance, 

 sulphide of potassium is a very readily soluble substance, which is 

 not disposed to enter into insoluble compounds even with the 

 matters within the animal body ; but owing to the readiness with 

 which it becomes oxidised, this substance does not pass into the 

 urine unchanged, but in the form of sulphate of potash, unless too 

 large a quantity have been introduced into the body. Many sub- 

 stances which enter into insoluble combinations with animal 

 matters, as, for instance, with the albuminates, only pass into the 

 urine when they have been conveyed into the organism in large 

 quantities ; hence Orfila found that the heavy metals, which are 

 not in general separated by the kidneys, namely, gold, silver, 

 lead, bismuth, antimony, arid arsenic, might be detected in the 

 urine, if administered in very large doses, but were commonly 

 found to be present only in the liver and its secretion, and, con- 

 sequently> also in the solid excrements, when they had been given 

 in relatively small and frequently repeated doses. 



Many organic substances undergo the same alterations in their 

 passage through the animal organism which have been artificially 

 produced by chemists; and this is especially the case with those 

 organic matters which have been decomposed into different sub- 

 stances by the application of certain oxidising agents ; there are 

 even many soluble substances which become so perfectly oxidised 

 in the blood, that neither they nor any of their products of decom- 

 position can be recognised in the urine. Many others, on the 

 contrary, which readily part with their oxygen, lose a portion of 

 it in their passage through the animal body, and very probably in 

 the prima via, which causes them to appear in the urine in lower 

 stages of oxidation. 



We have already seen (in vol. i., p. 4?) that after the use of 

 drinks containing a large quantity of carbonic acid., the amount of 

 the oxalate of lime in the urine is increased ; but we must here 

 observe, that we have found, from positive experiments, that the 

 free carbonic acid of the urine is also very considerably increased 

 by their use. After the use of champagne, the urine contains 53^- 

 of its volume of gas, and after that of Bavarian beer, 68-g-. 



It has been observed both by Buchheim and myself, that Seltzer 

 water did not produce the same effect as beer in the act of fer- 



