176 CIRCULATING FLUIDS: 



they are then filtered, the sulphate is washed with a little al- 

 cohol, and the alcohol is subsequently evaporated. The re- 

 sidue consists of hsematin with hajnifiphsein, a trace of fat, and 

 perhaps a little sulphate of ammonia. The latter may be 

 taken up by water, at the risk, however, of losing an almost 

 unappreciable trace of hsemaphsein, which is so far soluble in 

 that fluid, as to communicate a yellow tint to it. 



d. There may be certain cases in which the perfect sepa- 

 ration of the two colouring matters, the hsematin and hsema- 

 phsein, would be a matter of considerable importance. 



In all those cases in which I have found a large proportion 

 of hffimatiu, as in the blood in Bright's disease, and in men- 

 strual blood, a certain portion of hsemaphsein is always asso- 

 ciated with it. The dark coloured blood of melsena contains a 

 peculiarly large quantity of htemaphsein. The separation of the 

 two colouiing principles is best effected by alcohol, which dis- 

 solves the hsemaphffiin, but not the hsematin. The alcohol 

 should be warmed, but not allowed to boil. Upon the eva- 

 poration of the alcohol the haemaphsein is obtained, and when 

 thoroughly diied, may be weighed. 



II. a. By the evaporation of the alcoholic solutions, we ob- 

 tain a yellow or brown residue, which has a saltish taste, 

 and smells of extractive matters. It must be thoroughly 

 dried, and then weighed. 



b. If we wish to carry the analysis further, a known 

 weight of the residue must be incinerated. The quantity of 

 ash from 8 to 16 grains of this residue, will be small, pro- 

 bably from "3 to 1"0 grain. The residue likewise contains 

 sugar, urea, and the colouring matter of the bile ; the former 

 may sometimes be detected by the taste, and the presence of 

 the biliphpein may be recognized by the dark colour that it 

 imparts to the serum. In so minute a quantity of material 

 the urea cannot be easily traced. 



In my analj^ses of the blood, I have always followed this 

 course, and I feel convinced that if all necessary precautions 

 are taken, the results will be nearer the truth than those ob- 

 tained by any pre\dously described method. I do not, how- 

 ever, intend to assert that my method will give exactly ac- 

 curate results; and I shall at once proceed to point out, — 



