1. Curious form of uric acid crystals precipitated by the addition of nitric acid to Urine. These crystals have the form of quadrilateral pyramids.

2. Common form of Uric acid deposited in Urine.

3. Masses of uric acid crystals, often termed Cayenne pepper grains. The specimen from which the drawing was made, had been preserved in naphtha and creosote fluid* upwards of five years.

4. Common rhomboidal form of uric acid crystals from Urine.

5. Very large crystals of uric acid deposited from Urine after standing.

6. Six-sided crystals of uric acid. This form is not very common. It is distinguished from cystine by its colour, and by not being deposited in the same crystalline form when an ammoniacal solution has been allowed to evaporate.

How to work with the Microscope, page 36.

Portions of feathers, as would be supposed, often fall into the Urine, and the observer should render himself familiar with the characters of different varieties of common feathers.

Cotton fibres of various colours, as well as colourless, are often present in Urine, red and blue being perhaps those which are most frequently met with.

Fig. 7. Lozenge-shaped crystals of uric acid, precipitated by the addition of acid to Urine.

Fig. 8. Crystals of uric acid obtained by the addition of acid to Urine.

Figs. 9, 10. Curious forms of uric acid deposited in the Urine of a case of fatty degeneration of the kidney, magnified in different degrees.

Fig. 11. Mass of uric acid crystals with rhomboidal and fleur-de-lis forms, from Urine.

Fig. 12. Curious forms of crystals of uric acid from Urine.

Fig. 13. Amorphous mass, probably consisting of urate of soda with sharp crystals of uric acid projecting from it.