1869.] 



in the Blood and Urine 



19 



urinary solutions), the red colour is no longer destroyed by the mercurial 

 solution. 



Since, then, these difficulties are capable of removal, the argument by 

 the method of exclusion in favour of the red colour being due to sulpho- 

 cyanide of iron appears conclusive. There is in fact no other source from 

 which the red colour could proceed in the process by which the urine was 

 decolorized by milk of lime. 



Some salt of sulphocyanic acid must, then, be admitted to be a com- 

 ponent of the urine. 



For the detection of the salt it is only necessary to evaporate eight 

 ounces of urine in a water-bath. If milk of lime be employed as the 

 decolorizing agent which, for reasons already stated, is to be preferred, 

 the urine should be concentrated to a thick syrup. 



In the present stage of my inquiries many details are purposely omitted, 

 particularly those which refer to the quantitative determination of the 

 sulphocyanide in many different samples of urine. I may mention, how- 

 ever, that I found the average quantity present in healthy urine to amount 

 to about -J- of a grain in sixteen ounces. 



Since, then, a sylphocyanide was found in the urine, and was previously 

 known to exist in saliva, it was natural to look for it in other secretions. 

 It was therefore sought for in a large quantity of cow's milk, and in two 

 ounces of human sweat, but with negative results. 



Two ounces of pure pus from a cyst on a man's back were also ex- 

 amined, but no sulphocyanide was found. 



But as sulphocyanic acid was proved to exist in a secretion from which 

 it may be presumed to enter the blood, and also in an excretion derived 

 from the blood, it was to be expected that it would be found in the blood 

 itself. 



The blood operated on was in every instance diluted with an equal part 

 of distilled water. The mixture was then evaporated in a water-bath 

 until the red colour was altogether lost, and brown coagula, with appa- 

 rently little fluid, remained. The mass was strained through muslin by 

 pressure of the fingers. The filtrate was then decolorized by one of the 

 processes already described. Briefly stated, then, it was found that a 

 sulpho-cyanide exists in the blood of man, and in that of the pig, fowl, 

 turbot, salmon, and toad. 



I also found that when the serum of pig's blood, procured as free from 

 colour as possible and diluted with an equal portion of water, to prevent 

 complete coagulation, was treated with a solution of perchloride of iron, it 

 became red in a marked degree. This result has a special interest, because 

 it was obtained without any previous chemical manipulation, and the pre- 

 sence of a sulphocyanide was thereby proved. And this curious circum- 

 stance was also ascertained. If a few drops of a weak solution of sulpho- 

 cyanide of potassium be mixed with this reddened and diluted serum, and 

 the iron solution is again added, no increase of colour is produced. This 



c 2 



