66 THE BLOOD. 



a vein. Its specific gravity at 60 F. is, on an average, 

 1055, that of water being reckoned as 1000 ; the extremes 

 consistent with health being 1050 and 1059. Its tempera- 

 ture is generally about 100 F. ; but it is not the same in 

 all parts of the body. Thus, while the stream is slightly 

 warmed bypassing through the liver and some other parts, 

 it is slightly cooled, according to Bernard, by traversing 

 the capillaries of the skin. The temperature of blood in 

 the left side of the heart is, again 1 or 2 higher than in 

 the right (Savory). 



The blood has a slight alkaline reaction ; and emits an 

 odour similar to that which issues from the skin or breath 

 of the animal from which it flows, but fainter. The alka- 

 line reaction appears to be a constant character of blood 

 in all animals and under all circumstances. An exception 

 has been supposed to exist in the case of menstrual blood ; 

 but the acid reaction which this sometimes presents is due 

 to the mixture of an acid mucus from the uterus and 

 vagina. Pure menstrual blood, such as may be obtained 

 with a speculum, or from the uteri of women who die 

 during menstruation, is always alkaline, and resembles 

 ordinary blood. According to Bernard, blood becomes 

 spontaneously acid after removal from the body, owing to 

 conversion of its sugar into lactic acid. 



The odour of blood is easily perceived in the watery 

 vapour, or Jialitm as it is called, which rises from blood 

 just drawn : it may also be set free, long afterwards, by 

 adding to the blood a mixture of equal parts of sulphuric 

 acid and water. It is said to be not difficult to tell, by the 

 likeness of the odour to that of the body, the species of 

 domestic animal from which any specimen of blood has 

 been taken : the strong odour of the pig or cat, and the 

 peculiar milky smell of the cow, are especially easy to be 

 thus discerned in their blood (Barruel). 



