26 CHEMICAL PHYSIOLOGY. 



sulphate, when serum-albumin is precipitated. Sodic sul- 

 phate, however, gives no precipitate with pure serum. 



(b). Precipitate blood-serum with potassic phosphate. All 

 the proteids are thrown down after prolonged shaking. 



(c.) Precipitate blood-serum with magnesic sulphate and 

 sodic sulphate, or the double salt sodio-magnesic sulphate. 

 All the proteids are thrown down. 



15. Preparation of Fibrinogen. 



(a.) Dilute 10 cc. of hydrocele fluid with 150 to 200 cc. 

 of water, and pass through it for a considerable time a 

 stream of carbon dioxide, when there is precipitated a small 

 quantity of a somewhat slimy white body, fibrinogen. 



(b.) Take 10 cc. of hydrocele fluid and add powdered 

 crystals of common salt to saturation, as for the preparation 

 of paraglobulin (Lesson III., 13, A.) 



16. Coagulation Experiments. 



(a.} Andrew Buchanan's Experiment Mix 5 cc. fresh 

 blood-serum (preferably from horse's blood) with 5 cc. 

 hydrocele fluid, and keep the mixture at 35C. for some 

 hours, when coagulation occurs, a clear pellucid clot of 

 fibrin being obtained. 



(b.) To 5 cc. of hydrocele fluid, add some solution of para- 

 globulin (prepared as in Lesson III., 13, A); coagulation 

 will result after a time. 



(c.) Modify (a.) in the following manner : To 2 cc. of 

 fresh blood-serum, add 2 cc. of a solution of fibrinogen (pre- 

 pared as in Lesson IV., 15, b) = coagulation. 



(d.) To 2 cc. of salted plasma, prepared as in Lesson III., 

 10 (which is known to clot slowly on the addition of water), 

 add 10 volumes i.e., 20 cc. of a watery solution of fibrin- 

 ferment, prepared by the demonstrator = coagulation. 



17. The Salts present in blood are to be tested for in the usual 

 way. 



