COAGULATION RATE 215 



to five. The higher the haemoglobin content the greater the viscosity. Viscosity is 

 high in arterio-sclerosis and diabetic coma, low in the anaemias of nephritis. 



Coagulation Rate of Blood. This determination is of value in 

 connection with operations on jaundiced patients. 



Wright's coagulometer is a standard instrument but is cumbersome. 



A simple method of determining the rate is to take a piece of capillary glass tubing 

 and hold it downward from the puncture to let it fill for 3 or 4 inches. Then at inter- 

 vals of thirty seconds scratch with a file the capillary tubing at short distances and 

 break off between the fingers. When coagulation has taken place a long worm-like 

 coagulum is obtained. Normally coagulation occurs in about three to four minutes, 

 when the temperature is that of the hand in which the tubes are conveniently held. 

 Rudolf recommends placing the tubes in metal tube containers in a Thermos bottle 

 at 2oC. He gives the normal coagulation rate for this temperature as eight minutes, 

 while at a temperature below this the period is lengthened. Age and sex do not 

 influence the rate. Sabrazes, the originator of this method found no appreciable 

 variation in tubes from 0.8 to 1.2 mm. diameter. 



In Barker's test you mix a drop of blood and a drop of distilled water on a slide 

 and with a capillary tube sealed off at the end stir the mixture every half minute. 

 So soon as fibrin threads appear you have coagulation. 



SPECIFIC GRAVITY OF THE BLOOD 



Hammerschlag has a method for the determination of the Hb. 

 percentage based upon the specific gravity of the blood. 



In this method a mixture of benzol and chloroform is made of a specific gravity of 

 about 1050. A medium size drop of blood is then taken up with a pipette and intro- 

 duced below the surface of the mixture, carefully avoiding production of bubbles. 

 Variation in temperature introduces a very appreciable error. If it sinks add more 

 chloroform from a dropping bottle, if it tends to rise, more benzol. The mixture in 

 which the drop of blood tends to remain stationary, near the top of the mixed benzol 

 and chloroform, has the same specific gravity as that of the blood. This is deter- 

 mined by an accurately graduated hydrometer. The normal average specific 

 gravity for men is 1059, for women 1056. A table, giving the Hb. percentage cor- 

 responding to the specific gravity, accompanies the outfit. 



Eykmann controls the specific gravity of the drop of blood by adding a drop c 

 salt solution made to have a similar specific gravity. 



The specific gravity is reduced in all anaemias, especially chlorosis; in nephritis witl 

 osdema as well as in most cachetic states. 



In these latter the Hb. percentage may be normal. 



Specific Gravity in Cholera. To determine the necessity for intraven- 

 ous infusion in cholera Rogers has recently recommended the employ- 

 ment of small bottles containing aqueous solution of glycerine with 

 specific gravities varying from 1048^0 1070, increasing the spec 

 gravity in each successive bottle by 2. 



