50 



portions of lime is left, and this, much more soluble than bone- 

 phosphate, remains in solution. As the fermentation proceeds, 

 more lime is removed from the phosphate dissolved, until two 

 proportions of the three usually found in bone-phosphate are 

 actually combined with the other acids. In this fluid, bone- 

 phosphate of lime dissolves to a greater extent than in water, 

 and in the experiments we find it present, so long as excess of 

 bone-phosphate remains. Some experiments have shown that 

 the carbonic and crenic acids have the power of removing still 

 more lime from the mono-phos2")hate remaining, so that the solu- 

 tions approach the state of phosphoric acid dissolved and car- 

 bonate and crenate of lime deposited. This complex action has 

 heretofore escaped attention, probably from the fact that on add- 

 ing solution of ammonia, bone-phosphate of lime falls, and this 

 quantity of bone-phosphate was assumed to be the whole phos- 

 phate dissolved. If, however, the liquor from which the bone- 

 phosphate has been removed, be treated with solution of double 

 chloride of calcium and ammonium, a much more voluminous 

 pi'ecipitate is obtained, arising from the combination of free phos- 

 phoric acid with the new proportion of lime added. There are 

 other chemical relations of interest, but I advert to one only, — 

 the solution containing the mono-phosphate, and even phosphoric 

 acid, from the fermenting mass, is slightly alkaline, and it does not 

 lose this character when heated to the boiling point ; — long boiling, 

 ■with evaporation, gives rise to acidity, which manifests itself 

 slowly but decidedly. We can now explain the solution of the 

 phosphate of lime in the neutral fluids of the tissues in health, 

 and in the secretions and excretions where its presence is indi- 

 cated generally. 



In sea-water, and in bittern even, bones decompose and dis- 

 solve, but the act is never one of simple solution after the 

 organic changes commence. An elimination of lime by acids 

 momentarily present, converts the bone-phosphate into mono- 

 phosphate, which is a soluble salt, and can exist under the con- 

 ditions in presence of carbonate of lime and magnesian salts. 

 No difficulty attends the experiment of thus separating from 

 sea-water a phosphate containing at least three proportions of 

 phosphoric acid to one of lime, there being present at the same 

 moment in solution, the ordinary tris-phosphate, and in this 



