'250 ON THE COLOUR OF THE BLOOD, 



sier, and his tables of combinations of* the phosphoric acids 

 with salifiable bases in the order of affinity, clearly prove, 

 the doctrine of Fourcroyto be highly chimerical. — AlsoChap- 

 tal remarks " that phosphorus precipitates some metallic oxides 

 from their solution in the metallic state; phosphoric acid is 

 formed in this operation, which proves that the oxigene quits 

 the metal to unite with the phosphorus," and that " phospho- 

 ric acid acts only on a small number of metallic substances." 

 These arguments are sufficient to refute the theory of Mr. 

 Fourcroy, without the assistance of any additional ones. 



Mr. Davy, who has contributed much to the stock of che- 

 mical knowledge, denies that vital air is decomposed in respi- 

 ration, and endeavours to maintain, that the disengaged car- 

 bonic acid and water, are constituent principles of venous 

 blood, which are displaced by the vital air; for which the ve- 

 nous blood has a greater elective attraction, than for its con- 

 stituent elements, water and carbonic acid.— He also denies the 

 existence of caloric altogether, and says that oxigene gas con- 

 sists of oxigene and light, which he has denominated phos- 

 oxigene; from which he infers that in the process of respiration, 

 the phos-oxigene combines with the venous blood in the 

 lungs, and disengages the carbonic acid and aqueous gas from 

 it, and further, that the vermilion colour of the blood, is pro- 

 duced by phos-oxigene combining with it in its intire state. — 

 If it were a fact, that phos-oxigene combined with the blood 

 in its intire state, the blood instead of assuming the vermilion 

 colour, would in consequence of absorbing all the rays of 

 light, take on the appearance of absolute blackness. — Hence 

 his method of resolving the phenomenon of the red colour of 

 the blood is inadmissible. 



Mr Joseph Trent, who graduated in the University of Penn- 

 sylvania, A. D. 1800, observes that " light is a constituent of 

 oxigene gas, and that it is to the disengagement and operation 

 of this substance in respiration, that some of its phenomena 

 ought, in part, to be attributed, more especially the vermilion 

 colour of pulmonary blood." — I have endeavoured to give a 

 fair and judicious exposition of the different doctrines on the 

 vermilion colour of the blood, and shall now proceed to offer 



