On Sal Nifruin and Nitro-A'a'ial Spirit 103 



florid colour, although the blood at the bottom of the 

 vessel appears as a dark purple ; and yet it too if 

 exposed to the air will after a short time become 

 ruddy. So that it is not surprising that the blood in 

 the lungs, where the air diffused through all its 

 particles mixes intimately with it, is rendered florid 

 throughout. 



And now we remark that air mixed with blood 

 produces the ruddy colour in it, since it sets up 

 fermentation in its mass. For arterial blood which is 

 florid has its particles in motion and also effervesces 

 conspicuously, while the darker and duskier venous 

 blood is more grumous and is more quickly coagulated 

 on account of its feebler effervescence. 



The following experiment also corroborates the 

 view here taken. If blood that has been kept for 

 some time in a vessel be put into a glass from which 

 the air is exhausted by an air-pump, the blood at the 

 surface where it was of a florid colour will effervesce 

 gently and rise in bubbles. But if arterial blood 

 while still warm be put in a place void of air, it will 

 expand in a remarkable way and rise in an almost 

 infinite number of bubbles. And it is probable that 

 this results partly from the effervescence of its particles 

 and their being thrown into movement, and partly 

 from its particles being mixed with air. 



But to submit yet another experiment. If spirit of 

 nitre be poured upon a liquid saturated with volatile 

 salt and sulphur, such as the spirit of hartshorn 

 impregnated with its own oil, a very marked effer- 

 vescence and a very ruddy scarlet colour will be pro- 

 duced at once in the liquid, and yet this florid colour 

 changes into a dark purple when the liquid ceases to 

 effervesce. No doubt the nitro-aerial particles (and 

 we have elsewhere shown that the spirit of nitre 



