98 PROXIMATE ANALYSIS OF 



8. The residue not acted on by alcohol of '850 must be 

 dissolved in water, in which, if no protein-compounds are 

 present, it will dissolve without leaving a residue, although the 

 solution may not be clear. In this solution there will be con- 

 tained pyin, ptyalin, water-extract, phosphates, and perhaps 

 some chloride of sodium. The pyin is recognized by the 

 precipitate afforded by acetic acid. The ptyalin, when it is 

 present only in small quantities, and is mixed with extractive 

 matter, is not easily detected ; the onlj^ course we can adopt 

 is to precipitate the Avhole of the extractive matter of the 

 water-extract Avith the basic acetate of lead. A stream of sul- 

 phuretted hydrogen must then be passed through the fluid in 

 order to precipitate the lead. The liquid, after filtration or 

 decantation, must be evaporated to the consistence of a syrup, 

 and the ptyalin precipitated by alcohol. 



I may here remark that, in pursuing the directions laid 

 down in (7), we do not succeed in obtaining all the spirit- 

 extract that exists in the residue of (6). Hence in practice it 

 is better to dissolve the residue of (6) in a little water, so as to 

 reduce it to the consistence of a syrup, and then to precipitate 

 with alcohol of 'SSS. The salts may be obtained by incinerat- 

 ing a portion of the evaporated fluid. 



In the last six paragraphs we have assumed that no protein- 

 compounds arc present. If, however, this should not be the 

 case, — if some of the constituents of the blood, as, for instance, 

 globulin or hsematin, exist in the fluid, a diff'erent course must 

 be pursued. The presence of globulin and hsematin, and, con- 

 sequently, of albumen, may be easily ascertained. The fluid 

 must be boiled, evaporated on the water-bath to dryness, and 

 the residue reduced to a fine powder. The fat must be taken 

 up with ether, and the urea, alcohol-extract, bilin, with its 

 acids, and any haimaphaein and lactates that may be present, 

 with anhydrous alcohol. The residue must be boiled in spirit 

 of '915 until it ceases to communicate any additional red colour- 

 ing matter to that fluid. In this way we shall obtain the 

 globulin, haimatin, hffimaphsein, sugar, extractive matters, and 

 several salts, in a state of solution. The greater portion of the 

 globulin and hoematin is thrown down as the fluid cools ; the 

 turbid supernatant fluid is then evaporated on the water-bath 

 to a small residue, and treated with alcohol, which precipitates 



