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Art. XXVI.—On Formol for Preservation of Natural History Specimens.
[Read before the Wellington Philosophical Society, 22nd July, 1896.]
I Find that some of my natural history friends are unacquainted with formol, and, as I have had several letters asking about my way of using this drug, it has been suggested that possibly a few short notes might be useful to others.
In October and November last, Mr. Charles Smith, of Te Korito, Wanganui River, and myself made a trip to New South Wales, principally to obtain skeletons and fishes for the Public Museum, Wanganui. Our object was to get as many of the more interesting specimens as we could in the short time available. We wanted to spend as much time as possible in the field, and as little time as possible preparing specimens afterwards. We wanted something that would preserve our specimens after they had been roughly and quickly cleaned, and at the same time we were anxious not to be hampered with heavy and cumbersome impedimenta. Alcohol meant all this, as well as another big item to us—expense. I had heard and read of formol as a very strong antiseptic, so we determined to risk it. Formol was not procurable in New Zealand, but we found it kept in stock by Elliott Brothers, Sydney, the cost being £1 10s. per gallon. We were told that it would be unsafe to put formol in tin vessels, but, using it in such weak solutions, we risked that also; and I must say here that our specimens, when we reached home, turned out all we could wish. Our first hale was made amongst the “lobster-pot” men at Port Stephens. Kerosene-tins are to be had everywhere in the colonies, so we decided to trust to getting these useful vessels. There were only about a dozen fishermen in this little hamlet, yet we found plenty of tins. We had divided our formol in quarter-gallon tins for convenience, and packed one in each portmanteau. This was all that was required, except the few tools wanted. I never travelled so lightly on a collecting-trip before. I carefully cut an oval hole in the top or lid of the tin, so as to get the widest hole for large fishes. Then we half filled the tin with a 5-per-cent. solution of formol. The fishes are roughly skinned—that is, we left much of the flesh in the fins and head, &c.—and, giving the skin a rub inside with arsenical soap, rolled it carefully up and wrapped it in a piece of
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common calico, then packed it away in our tin. In this way we were able to pack away from fifty to a hundred skins of fish, &c., in one tin. We had rays, small sharks, &c., in numbers. An electric ray even is a very small-quantity when prepared in this way. We filled up our tin until we could not press any more in, then the hole was covered with part of a mustard-tin flattened out, and soldered down, so that there could be no fear of leakage. When two tins were finished in this way they were packed in a kerosene case, then labelled and shipped, and so on. With small fish, lizards, toads, frogs, &c., wanted for mounting, or small birds for skeletons, we only removed the viscera, and placed these small specimens amongst the other skins, of course wrapping each, specimen in the calico to save rubbing. The insects, land-shells, &c., we soaked in formol solution a few days, then packed in a mustard-tin with wool, sending them at once-home by the cheap “sample post.” I can hardly describe my anxiety upon reaching home to see how my specimens would turn out, nor my delight on finding them quite fresh, and many with the colours good. We found the blues and pinks the first to go, particularly so with the Crustacea and Cephalopoda. Since my return, in my spare time I have mounted many of the specimens, and have many more to do, and I find that these specimens, put into formol, 5-per-cent. solution, last October, are just as easily worked now, in June, as they were in December last, although the solution has been unchanged during that period. I mean to say that they are still in the original solution in which they were first placed.
Mr. Etheridge, the curator of the Museum at Sydney, showed me some small fish and Medusæ that had been in bottles for three months in formol, 10-per-cent. solution, that, looked far more fresh and the colours in better condition than one could possibly get with alcohol. I placed, in December last, our Physalia, with a small fish hanging in its tentacles, in a 5-per-cent. solution. The bottle has been standing, on our Museum window ledge, in full light, for six months. The specimen has faded, yet much of the pretty blue is left, nor is it anything like so opaque as if treated with alcohol. Owing to this experiment I intend, as soon as our fresh-supply of formol arrives, to treat all our what are called spirit-specimens in this way, if for no other reason than that of saving expense.
To sum up, I think there is no comparison between formol and alcohol—first, the formol is very much cheaper, the quantity needed for a kerosene-tin of 5-per-cent. solution costing, about 2s, for alcohol at least £1, and to this should be added the cost and great inconvenience of cartage and freight—not a small one when moving about; second, it does not
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evaporate; third, there is no danger from fire—and this is an item, for people will smoke and throw matches about, and how impossible it is to keep everything covered up; fourth, it does not require expensive apparatus to contain it; fifth, if takes up very little room; and, sixth, I believe the results are very much better.