CHEMICAL EXAMINATION OF THE SLOOP. 327 



To neutralize the blood, a -g-J-g- normal solution of tartaric acid is 

 used, which should contain an amount of alcohol sufficient to prevent 

 the growth of bacteria, but insufficient to precipitate the albumins 

 of the blood. The reagent may be prepared by dissolving 0.075 

 gramme of tartaric acid (Merck's crystals ; guaranteed reagent) in a 

 small amount of distilled water, adding 20 c.c. of alcohol (9394 per 

 cent.), and diluting to 200 c.c. with water. 



For the spectroscopic examination a Browning instrument will 

 suffice. A detailed description accompanies the instrument. 



The Chemical Composition of the Blood as a Whole. 



As the blood constitutes the most important channel through 

 which the food-stuifs reach the various tissues of the body, and 

 through which waste matter is carried away, we may expect to 

 find here representatives of both classes of substances. This is 

 actually the case ; but as the waste matter is rapidly eliminated, 

 representatives of this group are normally present in only very 

 small amounts. Certain food-stuffs, moreover, which are not im- 

 mediately required by the body in large quantities, such as fats and 

 carbohydrates, are likewise present only in traces. They are stored 

 in various tissues of the body until needed, but even then only 

 small quantities appear in the blood at one time. The only food- 

 stuifs, in fact, which are always present in the blood in large quan- 

 tities, are the albumins. These, however, must be sharply separated 

 into two classes, viz., into those which are normally present as 

 integral constituents of the cellular elements of the blood, and into 

 the circulating albumins of the plasma. In addition to these ele- 

 ments, we also meet with mineral salts, a very large amount of 

 water, and with certain gases. 



A general idea of the chemical composition of human blood 

 may be had from the following table, which is calculated for 1000 

 parts by weight : 



Ked corpuscles 1 .... ................. 480.00 



Water ....................... 276.90 



Oxyhsemoglobin ................... 193.90 



Stroma 2 ...................... 9.12 



Plasma ......................... 520.00 



Water ....................... 477.36 



Albumins ...................... 35.88 



Extractives ..................... 2.39 



Inorganic salts ................... 4.36 



From this analysis it will be seen that almost one-half of the 

 total weight of the blood is referable to cellular elements, and that 

 in the liquid portion proper there is not more than 8.2 per cent. 

 of solids, of which 6.9 per cent, is represented by albumins, 0.84 

 per cent, by mineral salts, and 0.46 per cent, by extractives. 



1 The white corpuscles, because insignificant in amount, have been ignored 



2 This includes mineral salts. 



