*Chromic and nitric fluid.*--This is made as follows:-- Chromic acid 1 gramme 45 grains. Nitric acid 2 grammes 1-1/2 drachms. Water 200 c.c. 1 pint. If the bone is not very compact the fluid may be used diluted with an equal quantity of water. A large quantity of fluid should be used, and like all decalcifying fluids, it should be frequently changed. As soon as the specimen is sufficiently flexible, it should be thoroughly washed in running water for some hours, and then transferred to spirit until it is convenient to cut sections. *Von Ebner’s solution*:-- Hydrochloric acid 1 gramme 1-1/2 drachms. Common salt 10 grammes 2 ounces. Water to 100 c.c. 1 pint. It is a very useful decalcifying agent, but causes the fibrous elements to swell up rather more than chromic and nitric fluid. A large quantity of the fluid must be used, and it should be changed daily. It must be very thoroughly washed out in running water when the decalcification is completed. *Bleaching solution* (eau de Javelle). (1) “Chloride of lime” (bleaching powder) 20 1/2 oz. Water 100 2-1/2 oz. Shake up well. (2) Carbonate of potassium 20 1/2 oz. Water 100 2-1/2 oz. Mix the two solutions. Allow them to stand for an hour and filter. It is used chiefly for clearing vegetable sections but may also be used for sections containing a large quantity of pigment. It is particularly useful in decolourizing sections of “madura foot” due to the presence of a black fungus. CHAPTER III. SECTION CUTTING. *Embedding of sections.*--Before sections are made the tissues require to be embedded in some fluid, which will permeate their interstices, and is capable of being rendered firm so as to support the most delicate parts when the knife passes through the tissue. The most generally useful substances are:-- (1) gum, (2) celloidin, (3) paraffin or wax. *Gum.*--_Picked_ colourless gum arabic 2 parts, cold water 3 parts. Leave with frequent stirring until dissolved. Add ten drops of carbolic acid to each ounce of the mucilage. Specimens are thoroughly freed from all trace of the hardening fluid by washing in water, and the tissue is then placed in the gum solution for at least twelve hours, or if enough carbolic acid be added, it may be left there for an indefinite time. When frozen, gum forms a firm non-crystalline mass, which supports the tissue on all sides. It must not be frozen too deeply, or it becomes hard and rather brittle and is apt to injure the razor. If this have occurred the surface can be softened sufficiently by breathing gently on it.