PLASMA AND SERUM. 51 



of uranic salt is present, it can be detected by potassic ferrocyanide, which 

 gives a brown colour with uranic salts. 



The standard uranic nitrate solution contains 35*5 grammes in a litre. One 

 c.c. corresponds to O'OO$ gramme P 2 O 5 . 



To 50 c.c. of urine add 5 c.c. of a solution containing 100 grammes of sodic 

 acetate in 900 c.c. of water, to which 100 c.c. of glacial acetic acid have been 

 added. Heat the 55 c.c. to 80 C. Add the uranic nitrate solution, until a 

 drop of the mixture placed on a white porcelain slab gives a distinct brown 

 colour, with a drop of potassic ferrocyanide. Note the quantity of solution 

 used and calculate therefrom the percentage of P 2 O 5 in the urine. * 



IX. Blood Plasma and Serum. 



*+* The experiments described in this section cannot be satisfactorily carried out in warm 



weather. 



1. Dilute about I c.c. of sodic sulphate plasma (obtained by collecting 

 blood in one-third of its volume of saturated solution of sodic sulphate) with 20 

 times its volume of water and place in a water-bath warmed to about 35 C. ; it 

 will probably coagulate in about 20 to 30 minutes. 



2. To a second similarly diluted liquid add a drop or two of solution of 

 "blood-ferment " (prepared by precipitating serum with alcohol, collecting the 

 precipitate, drying in vacuo and extracting with water). The addition of this 

 solution promotes coagulation. 



3. To 2-3 c.c. of pericardial fluid (from the horse) or hydrocele liquid add a 

 little serum and place the mixture in a warm bath ; it will coagulate. 



4. Saturate about 5 c.c. of pericardial fluid with sodic chloride, by adding 

 finely-powdered salt, and shaking ; a proteid substance separates and forms a 

 thick scum on the surface. Pour off the liquid, dissolve the scum in water, 

 add a few drops of serum, and place in the warm bath ; the mixture will 

 coagulate. 



5. Precipitate about 5 c.c. of sodic sulphate plasma as in 4, dissolve the 

 sticky precipitate in water and place in the warm bath ; the solution will 

 coagulate. 



6. Acidify 5-10 c.c. of serum with a drop of acetic acid and boil, filter off 

 the albumin and evaporate the residue. Sodium chloride crystallizes in aggre- 

 gations of cubes. 



7. Dilute i part of serum with 15 parts of water, add a drop or two of 

 dilute acid (o'l per cent.). Paraglobulin is precipitated (see iv, 2, a). 



* For details as to the hypobromite method, see Dupre's original paper in 

 the Journal of the Chemical Society, 1877, vol. i. p. 534. 



The method for the determination of P 2 O 5 is practised in this class as an 

 example of a volumetric process. For other methods relating to the urine 

 consult Handbook for the Physiological Laboratory, pp. 545-558. It is 

 important to remember, that in order to obtain trustworthy results, as 

 scrupulous care must be taken in the measurement and collection of the urine 

 passed during the period of observation as in the analytical procedures. 



E 2 



