An inexpensive preservative may also be made by dissolving chloride of zinc--about one ounce to the pint of water. This is considered by some to be one of the best fluids for keeping animal structures in good condition. Now, although the different fluids here mentioned are described in connection with the _temporary_ preservation of natural objects, it must be remembered that they are equally adapted for the permanent preservation of the animals and plants that are to figure in the museum of the sea-side naturalist; and, although some marine objects may be preserved in a dry state in a manner to be hereafter described, yet there are many species of animals, and also some plants, that can be satisfactorily preserved only by immersion in a suitable fluid. This method may be applied to all soft-bodied animals, such as anemones, jelly-fishes, marine worms, shell-less molluscs (sea slugs, cephalopods, &c.), the soft parts of shelled molluscs, fishes, &c.; and most sponges retain their natural appearance much better in a preservative fluid than in a dry condition. Many sea-weeds also, which are practically destroyed by the most careful drying process, are most perfectly preserved in fluid. But the puzzled amateur will probably be inclined to ask: ‘Which is the best preservative liquid for this or that specimen?’ No satisfactory general rule can be given in answer to such a question, and a great deal will have to be determined by his own experiments and observations. Whenever he has two or three specimens of the same object, as many different fluids should be employed, and the results compared and noted. In this way a very great deal of useful information will be obtained and by the best possible means. However, it may be mentioned that all the fluids alluded to above may be safely used for almost every animal or vegetable specimen with the following reservations: strong spirit should not be employed for _any_ very soft animal, nor should it be used for delicate green plants, since it will dissolve out the green colouring matter (_chlorophyll_), leaving them white or almost colourless. Further, the greatest care should be exercised in dealing with sea anemones and jelly-fishes. If spirit is used for preserving these creatures, it should be very dilute, at least at first, but may with advantage be increased in strength afterwards, though this should be done gradually. Whatever be the preservative used, it is sure to be more or less charged with sedimentary and coloured matter extracted from the object immersed in it; hence, if the specimen concerned is to form part of a museum collection, it will be necessary to transfer it to a fresh solution after a time, and a second, and even further changes may be necessary before the object ceases to discolour the fluid or render it turbid.