92 PROXIMATE ANALYSIS OF 



If the fluid be very viscid and tenacious^ mucus-corpuscles 

 are sure to be detected by the microscope : should it yield an 

 ammoniacal odour as if decomposition were going on^ the 

 viscidity may be due to the action of the ammonia that has 

 been formed. 



4. If the fluid have an acid reaction, a free acid must be 

 present. In most cases this is lactic/ occasionally however 

 acetic acid. The latter acid may be recognized by the pe- 

 culiar odour evolved on the application of heat. It may 

 also be recognized (if the fluid be not very deeply coloured) by 

 the blood-red tint that is produced by the addition of the 

 perchloride of iron, after the free acid has been thoroughly 

 neutralized by ammonia. If acetic be the only free acid, by 

 the time the fluid has been evaporated nearly to dryness, all 

 acid reaction will have disappeared ; if however free lactic acid 

 be present, the residue which is left after evaporation will still 

 have an acid reaction. 



If the fluid have an alkaline reaction, either a free alkali or 

 an alkaline carbonate must be present. Free ammonia may 

 be recognized by its peculiar odour, and by the vapour which 

 is developed on the approximation of a glass rod moistened 

 with hydi'ochloric acid. 



5. If the fluid have a sweetish taste, it contains sugar. 

 The sweetness is however sometimes not preceptible until the 

 fluid has been evaporated to the consistence of a syrup, or even 

 till the syrup has been treated with alcohol of -900, and the 

 alcoholic solution evaporated. When the presence of sugar 

 is suspected, the various tests mentioned in page 67, more 

 especially Trommer^s test, should be applied. If the fluid has 

 a bitter taste, more or less resembling that of bile, it contains 

 either bilin or the products of its metamorphosis. The indica- 

 tions aftbrded by a well-marked saline or acid taste are 

 sufficiently obvious. 



6. If the fluid be of a blood-red colovir, we may conclude 

 that hsematin is present ; and if blood-corpuscles are detected 

 by the microscope, we have certain proof of the existence of 

 hsematin, globulin, and albumen. Globulin and hsematin may 



' [The presence of this acid in the animal fluids has been recently disputed by 

 Liebig and Enderling ; there are, however, too many chemists \vho assert that they 

 have detected it, to allow us to regard the question as settled in the negative.] 



