BLOOD. 187 



sugar that it was readily detected by the taste ; on another 

 occasion, however, it was only rendered manifest on the addi- 

 tion of sulphuric acid. But of all the tests for sugar in the 

 blood, Trommer's is certainly the best. The protein-compounds 

 are first precipitated with anhydrous alcohol, and dry carbonate 

 of potash is then added to the filtered spirituous solution, 

 which must be well shaken. On the addition of a little solution 

 of sulphate of copper, and the application of heat, we observe, 

 if sugar be present, a yellow or yellowish brown tint developed, 

 produced by the reduction of the copper to a state of suboxide. 



3. Bile. In healthy blood we find neither bilin nor bili- 

 phsein. In icterus we meet with bilipluein in the serum, which 

 is more or less deeply coloured in proportion to the quantity 

 of this pigment contained in it. It may be of a deep orange, 

 or almost red colour, so as to lead to the suspicion of the 

 presence of hsematin in a state of solution. I found the serum 

 nearly blood-red in a case of icterus ; but on shaking it against 

 the sides of the vessel, the thin adhering layer appeared of a 

 beautiful safi'ron colour. A similar colour was induced by the 

 addition of water to the serum. 



If only so small a quantity of biliphsein be present as to 

 colour the serum slightly, it may be recognized by the addition 

 of nitric acid, which produces a variety of tints, more or less 

 green in their character. The albumen is at the same time 

 precipitated in white flocks, upon which a slight tinge of green 

 may be distinctly perceived. ^ In the deep red serum already 

 alluded to, the addition of nitric acid produced an intensely 

 clear grass-green colour, which, at some points, passed into a 

 blue, and, in the course of twenty-four hours, into a yellow 

 tint. The quantity of biliphsein varies directly with the intensity 

 of the colour of the serum, and with the time required for the dis- 

 appearance of the green tint, produced by the addition of nitric 

 acid. Neither in the blood already alluded to, nor in another 

 specimen which contained less biliphsein, could I discover a 

 trace of bilin. The alcohol-extract of the blood had a saltish, but 



' [In consequence of the facility with which coagulated albumen assumes a green 

 tint under these conditions, we are often enabled to detect liilipha;in (that would 

 be otherwise unappreciable) in non-albuminous fluids, by the addition of a little 

 albumen.] 



