Dissolve 600 grains potash alum in ten fluid ounces of water, and add to this, under constant boiling, a solution of carbonate of soda until a slight permanent precipitate is produced. Filter and add water up to sixteen ounces. Boil and add the solution to the cold ammoniacal solution of carmine in the Winchester quart, and shake vigorously for a few minutes. A drop of this placed upon white filtering-paper should show no coloured ring. If much colour is in solution the whole must be rejected, because, although it is possible to precipitate all the colouring matter by the addition of ammonia or alum, it is not well to do so, as the physical condition of the precipitate is thereby altered. Supposing the precipitation to be complete, or very nearly so, shake vigorously for at least half an hour, and allow it to stand until quite cold. The shaking must then be renewed for some time, and the bottle filled up with pure water. After allowing the precipitate to settle a day, draw off the clear supernatant fluid with a syphon. Repeat the washing until the clear liquid gives little or no precipitate with chloride of barium. So much water must be left with the colour at last that it shall measure forty fluid ounces. For the injecting fluid take twenty-four ounces of the above coloured liquid, and three ounces of good gelatine. Allow these to remain together twelve hours, and then dissolve by the heat of a water bath; after which it should be strained through fine muslin. As this injecting fluid contains gelatine, the hot water, and other contrivances mentioned in a former part of the chapter, will be necessary here also, but no peculiar treatment will be required. CHAPTER VII. MISCELLANEOUS. It must be evident to all readers that there are various objects of interest to the microscopist which cannot be properly placed amongst any of the forementioned classes, but must not be omitted in such a guide as this professes to be. Of these may be mentioned the circulation of the blood in various animals, the rotary motion of the fluid in many plants, the best means of taking minute photographs, &c. &c.