Chloride of zinc, 1 part.
Water, 20 parts.
This formula appears to be one of the non-alcoholic preservatives most suited for fishes in preparation jars. I have so lately tried it that I cannot at present state if it is the very best.
PICRIC ACID, formed by a certain chemical fusion of carbolic acid with nitric acid, is recommended (when diluted) for the preservation of soft-bodied animals, such as zoophytes, etc..
[BICHROMATE OF POTASH (see chapter IV), though so useful for] pickling fishes, mollusca, worms, and even "jelly fish" and sea-anemones, is, I have found, liable to be attacked by mildew; to prevent this add a few drops of phenic (carbolic acid). [Footnote: Phenol, Phenic Acid, Phenic Alcohol, Hydrate of Phenyl (C6H5HO)=Carbolic add.] This salt is also used in microscopy to assist in fixing glass covers on glass slides. The cement in question appears so admirably adapted to many purposes, that I think it worth quoting (see Science Gossip, 1879, p. 136):
Cox's gelatine, 2 oz.
Acetic acid, fluid, 1 drachm.
Gum ammoniac, 10 grains.
"Dissolve in a water bath, and filter through cotton while warm. This cement remains fluid when cold, and dries quickly. After the ring has become set, or stiff, the whole slide is immersed for a minute or so in a 10-grain solution of bichromate of potash, and is then allowed to dry, exposed to the light, which makes the bichromated gelatine perfectly insoluble, even in boiling water, and thoroughly prevents the escape of any glycerine."
PERMANGANATE OF POTASH (see chapter IV) is recommended at p. 49, Science Gossip, 1879, by a French scientist, for "preserving delicate organisms." "It is especially good in histological researches, as it acts like osmic acid, burning up the protoplasm, bringing out the minutiae, and showing the nuclei, outlines of cells, etc.. It is used as a saturated solution in distilled or very pure spring water; sea-water also dissolves it. The concentrated solution, of a lovely violet colour, kills small organisms at once, and then burns them. They are left in it from thirty minutes to an hour, then withdrawn, and placed in alcohol, after which they can be made transparent with essence of terebinth and mounted in Canada balsam. Beautiful results are thus obtained with echinoderms, zoophytes, worms and marine arthropoda. For delicate researches, especially in the ciliated infusoria, it is better than osmic acid, without its great cost, and is everywhere easily obtained." — G. du Plessis.