52 IMMEDIATE PRINCIPLES OF THE TISSUES. 



the pineal gland, on the plexus choroides, &c. ; but otoconites are 

 formed entirely of carbonate of lime, in crystals of the rhomboidal 

 form, which is peculiar to it. 



It is, doubtless, in a solid state in bones, teeth, and cartilage, and 

 in the concretions before mentioned. It is certainly in a liquid state 

 in the blood, but not in direct solution, since water very slightly 

 dissolves it. The chloride of potassium and the carbonic acid there 

 may aid in its solution, since both the former and also a fluid con- 

 taining the latter acid dissolve it in a slight degree. In bone and 

 cartilage the carbonate is doubtless united with the phosphate of 

 lime before being combined (in company with it) with the organic 

 bases (osteine and cartilageine) to form the fundamental organized 

 substance of these two tissues. It is derived, in the organism, from 

 spring water holding carbonic acid in solution, and also from the 

 other salts of lime in the food. 



Finally, much of the carbonate of lime found by calcination of 

 tissues, &c., whence it is derived, may be formed by this process 

 itself; since all the salts of lime which have a combustible acid (e. g. 

 the lactic) are thus converted into the carbonate of lime. 



6. Carbonate and Bicarbonate of Soda. (NaO.C0 2 & Na0.2C0 2 + HO.) 

 The first of these salts is found in the blood, feces, saliva ; in the 

 urine, when alkaline, without being ammoniacal ; and in osteo-sar- 

 coma. Valentin also found about one-third of one per cent, of it 

 in the compact tissue of healthy bone. It is always, in the organ- 

 ism, dissolved in water, and therefore liquid or solid, as may be the 

 case with the water itself. In blood it constitutes 0.1628 per cent., 

 and in feces .08 per cent. To it is due the alkaline reaction of the 

 blood, the saliva, and the cerebro-spinal fluid. It is combined with, 

 and dissolves, the albumen of the blood; and even prevents the 

 fibrin from coagulating, if the blood drawn from a vein falls into a 

 vessel containing a solution of this salt. It maintains the elasticity 

 and the firmness of the blood-globules, conditions without which 

 haematosis cannot be secured. (Robin and Verdeil.) 



A very little of this salt is derived from water and food ; it is 

 almost wholly formed in the body. The malates, citrates, tartrates, 

 and lactates of soda and of potassa, contained in fruits taken as 

 food, are all converted into the carbonate of these two salts respect- 

 ively, and thus appear in the urine. The hydrogen lost by these 

 acids, on being converted into the carbonic, is said to have been 



