CALCIUM PHOSPHATE AND CALCIUM CARBONATE. 311 



EXPLANATION OF PLATES. 



Plate i. 



All figures are from camera lucida tracings and are of equal magnification, 

 X 200, so that the relative size of precipitated particles in each case can be 

 compared. Only forms which were common, and appeared in quantity have 

 been shown. 



All illustrations are to show forms assumed by calcium carbonate precipi- 

 tated from various solutions by the reagents listed below. 



Fig. 1. Crystals of calcium carbonate precipitated by sodium carbonate in 

 distilled water. 



Fig. 2. Crystals of calcium carbonate precipitated by ammonium carbonate 

 in distilled water. 



Fig. 3. Crystals of .calcium carbonate precipitated by potassium carbonate 

 in distilled water. 



Fig. 4. Deposit of calcium carbonate precipitated by sodium carbonate in 

 distilled water containing 0.1 per cent, lecithin. Note small spherules, and 

 small crystals, a tendency towards clumping, a very large spherule and a large 

 rosette. 



Fig. 5. Deposit of calcium carbonate precipitated by ammonium carbonate 

 in distilled water containing 0.1 per cent, lecithin. Spherules of various sizes, 

 a marked tendency to fusion, and formation of large irregular masses are to 

 be noted. 



Fig. 6. Deposit of calcium carbonate precipitated by potassium carbonate 

 in distilled water containing 0.1 per cent, lecithin. Note a tendency to clump- 

 ing, various sizes of spherules with some double forms. The last three fortes 

 indicate one process of disintegration of a spherule, by the occurrence of radial 

 lines along which it splits into sectors, which thus become triangular crystals. 



Fig. 7. Deposit of calcium carbonate precipitated by sodium carbonate in 

 a solution of egg albumen. Practically the whole precipitate was in form of 

 spherules. 



Fig. 8. Deposit of calcium carbonate precipitated by ammonium carbonate in 

 a solution of egg albumen. Spherules of varying size are seen, also some crys- 

 tals. 



Fig. 9. Deposit of calcium carbonate precipitated by potassium carbonate 

 in a solution of egg albumen. Many spherules are seen, and a tendency to- 

 wards fusion is noted. 



Fig. 10. Deposit of calcium carbonate precipitated by sodium carbonate in 

 a solution of egg albumen containing 0.1 per cent, lecithin. Note the markedly 

 increased size of spherules and crystals and the tendency to fusion. 



Fig. 11. Deposit of calcium carbonate precipitated by ammonium carbonate 

 in a solution of egg albumen containing 0.1 per cent, lecithin. Note the in- 

 creased size of particles, and their tendency to fuse. 



Fig. 12. Deposit of calcium carbonate precipitated by potassium carbonate 

 in a solution of egg albumen containing 1 per cent, of acetone. Crystals and 

 spherules both occur. One crystal is seen fused with a spherule. 



Fig. 13. Deposit of calcium carbonate by interaction of calcium chloride 

 in a 1 per cent, gelatin solution with sodium carbonate in a 4 per cent, gelatin. 



