Sodic Phosphate, . 015 per 1000 

 Calcic Phosphate, . \ o-*q 

 Masrnesic 



GASES OF THE BLOOD. 39 



; III. Traces of Grape-Sugar [0-1 to - 15 per cent, (more in the hepatic vein, 

 0*23 per cent.)] derived from the liver and muscles, and increased after haemorrhage 

 { 175) ; some glycogen, and another reducing fermentative substance also 

 increased by haemorrhage. 



The amount of grape-sugar in the blood increases with the absorption of sugar from the 

 intestine, and this increase is most obvious in the blood of the portal and hepatic veins ; there 

 is also a slight increase in the arterial blood, but there it is rapidly changed. The presence of 

 sugar is ascertained by coagulating blood by boiling it with sodium sulphate, pressing out the 

 fluid and testing it for sugar with Fehling's solution (Ol. Bernard). Pavy coagulates the blood 

 with alcohol. 



IV. Extractives. Kreatin, urea (0*016 per cent., increased after nitrogenous 

 food), succinic acid, and uric acid (more abundant in gouty conditions), guanin (?), 

 carbamic acid, sarcolactic acid ; all occur in very small amounts. 



V. Salts (0*85 per cent.), especially sodic chloride (0'5 per cent.) and sodic 

 -carbonate. [It is most important to note that the soda salts are far more abundant 

 in the serum than the potassium salts. The ratio may be as high as 10 : 1.] 

 Animal diet increases the amount of salts, vegetable food diminishes it tempo- 

 rarily. 



Salts in human blood-serum (Hoppe-Seyler). 

 Sodic Chloride, . . 4-92 per 1000 

 ,, Sulphate, . 0*44 ,, 



,, Carbonate, . 0'21 ,, 



If large quantities of salts are introduced into the blood, they almost entirely disappear from 

 the blood-stream within a few minutes, chiefly by diffusion into the tissues. They are gradually 

 eliminated by the kidneys. The same is true of sugar and peptones (Ludurig and Klicoicicz). 



VI. Water about 90 per cent. 



VII. A yellow pigment. 



The pigment m&y be extracted with methylic alcohol. It shows two absorption-bands of a 

 lipochrome like lutein (Krukenberg). Thudichum regards the pigment of the serum as lutein ; 

 Maly, as hydrobilirubin : and MacMunn as choletelin. 



33. THE GASES OF THE BLOOD. Absorption by Solid Bodies. A considerable attraction 

 exists between the particles of solid porous bodies and gases, whereby the latter are attracted and 

 condensed within the pores of solid bodies, i.e., the gases are absorbed. Thus, 1 volume of 

 boxwood charcoal (at 12 C. and ordinary barometric pressure) absorbs 35 volumes C0 2 , 9*4 

 vol. O, 7 '5 vol. N, 175 vol. H. Heat is always formed when gases are absorbed, and the 

 amount of heat evolved bears a relation to the energy with which the absorption takes place. 

 Non-porous bodies are similarly invested by a layer of condensed gases on their surface. 



By Fluids. Fluids can also absorb gases. A known quantity of fluid at different pressures 

 always absorbs the same volume of gas. Whether the pressure be great or small, the volume of 

 the gas absorbed is equally great ( W. Henry). But according to Boyle (1662) and Mariotte's 

 law (1679) on the compression of gases, when the pressure within the same volume of gas is 

 increased, the volume varies inversely as the pressure. Hence it follows that, with varying 

 pressure, the volume of gas absorbed remains the same, but the quantity of gas (weight) is 

 directly proportional to the pressure. If the pressure = 0, the weight of the gas absorbed must 

 also = 0. As a necessary result of this, we see that (1) fluids can be freed of their absorbed 

 .gases in a vacuum under an air-pump. 



Coefficient of Absorption means the volume of a gas (0 C.) which is absorbed by a unit of 

 volume of a liquid (at 760 mm. Hg) at a given temperature. The volume of a gas absorbed, 

 and therefore the coefficient of absorption, is quite independent of the pressure, while the weight 

 of the gas is proportional to it. Temperature has an important influence on the coefficient of 

 absorption. With a low temperature it is greatest ; it diminishes as the temperature increases ; 

 and at the boiling-point it = 0. Hence, it follows that (2) absorbed gases may be expelled 

 from fluids simply by causing .the fluids to boil. The coefficient of absorption diminishes for 

 different fluids and gases, with increasing temperature, in a special, and by no means uniform, 

 manner, which must be determined empirically for each liquid and gas. Thus the coefficient 

 of absorption for C0 2 in water diminishes with an increasing temperature, while that for H in 

 water remains unchanged between and 20 C. 



Diffusion of Gase3. Gases which do not enter into chemical combinations with each other 

 mix with each other in definite proportions. If the necks of two flasks be placed in communi- 

 cation by means of a glass or other tube, and if the lower flask contain C0. 2 , and the upper one 

 H, the gases mix quite independently of their different specific gravities, both gases forming in 



