56 L. Gmelin and F. Tiedemanris [Jan. 



liquid. When heated in a pneumatic apparatus, carbonic 

 acid escaped. 



Dr. Stevens observed that the colouring matter of the 

 blood is at first dark, but at last black. In this state it 

 is obtained, when the coagulum is digested in distilled 

 water and the salts thereby removed. The dark hue of the 

 colouring matter is quickly changed to arterial red, when 

 it is brought in contact with the neutral salts, and the red 

 colouring matter becomes dark when added to acids, even 

 carbonic acid. The veinous blood contains free carbonic 

 acid, which can be removed, not only by exposure to the 

 atmosphere, but even to hydrogen at common temperatures. 

 By these means, he explains the difference between arterial 

 and veinous blood. Hermann states, that he had made simi- 

 lar observations previously. 



It has been shewn, (Ann. de Chimie xix.J that when 

 arseniate or phosphate of soda appear in a solution, which 

 with the addition of arsenic or phosphoric acid, exhibits an 

 alkaline re-action, the liquid after crystallization is strongly 

 acid ; but if potash is the base of the crystallized salt, then 

 the solution is alkaline. In the first case the salt is neutral, 

 in the last, acid. Litmus paper moistened with a solution 

 of biphosphate or binarseniate of potash becomes red, dried 

 it becomes blue, when the salt by crystallizing takes up 

 the acid, which reddened the litmus paper. 



Article X. 



Researches on the Blood. By L. Gmelin and F.Tiedemann, 

 assisted by E.Mitscherlich. Poggendorffs Annalen xxxi. 



Observers have differed with regard to the presence of 

 carbonic acid in the blood. 



Vogel found that under the receiver of an air pump, lime 

 water was acted on by the disengaged carbonic acicl. 



Scudamore obtained in the same way, by means of barytes 

 water, a precipitate of carbonate of barytes, equivalent to 

 J or ^ cubic inch of carbonic acid gas, from six ounces of 

 blood. 



Brande procured from one ounce of arterial or veinous 

 blood 2 cubic inches of carbonic acid. 



