PLATE 8. Crystals from Animal Secretions, 



Figure 



1 . Uric acid ; human, natural. a, rhombs, front view, b, side view ; c, d, striated ; 



e, rhombs with obtuse angles truncated ; f t twin crystals ; g, ditto ; h, hour- 

 glass crystals ; , nucleated ditto ; k y l t m, n, o (and lower h), aigrettes ; p, large 

 dumb-bell forms. 



2. Uric acid; human, natural, a, front, 6, side view. 



3. Uric acid, coloured artificially by murexide (these crystals should have been 



coloured pink instead of yellow). 



4. Uric acid, natural, a, front, 5, side view ; c, aigrette. 



5. Uric acid, precipitated from solution in sulphuric acid by water. 



6. Uric acid, rhombs, slightly acted upon with potash, showing spurious nuclei. 



7. Uric acid, precipitated from gout- stones. 



8. Uric acid of Boa, artificially precipitated, a d, from solution in sulphuric acid 



by water ; e A, from solution in potash by muriatic acid. 



9. Uric acid, precipitated from the excrement of the tortoise. 



10. Uric acid, precipitated from the excrement of the clothes-moth. 



1 1 . Urate of soda and ammonia. , spheres with nuclei and concentric rings, arti- 



ficial ; b, surface covered with radiating needles ; c, d, e, natural forms ; 

 /, g, artificial. 



12. Urate of soda. , artificial, deposited on cooling of an aqueous solution; 



, natural, as composing the chalky matter around gouty joints. 



13. a, b, Urate of lime. 



14. a, 6, Urate of magnesia. 



15. Uric acid, precipitated by an acid from human urine. 



