“A strong infusion of colocynth and quassia, spirits of turpentine, expressed juice of green walnuts, and pyroligneous acid, have all been proposed. In hot climates the ravages of the Anobium on books have been prevented by washing their backs with a fluid compound of corrosive sublimate (ten grains) and four ounces of alcohol, and the paste used in the book covers is there also mixed with alcohol.”
Sir H. Davy and Professor Faraday hesitated to employ corrosive sublimate as a means of preventing the ravages of the bookworm in Earl Spencer’s library, at Althorp, not feeling certain as to whether the quantity of mercury used would affect the health of the inhabitants. Amongst all the combinations of mercury, perhaps the bi-chloride, or corrosive sublimate, is the most terrible poison. It should be remembered that there are two chlorides of mercury—one the proto-chloride, ordinarily known as calomel; the other, bi-chloride, ordinarily known as corrosive sublimate; the respective compositions of which are as follows:
| Calomel, and Corrosive Sublimate. | Parts by Weight. | |
|---|---|---|
| Chlorine. | Mercury. | |
| Calomel, or proto-chloride of mercury | 36 | 200 |
| Corrosive sublimate, or bi-chloride of mercury | 72 | 200 |
Hence the ratio of chlorine in these two chlorides is as one to two.
Botanists have long used a solution of corrosive sublimate in alcohol, known by the name of Smith’s solution, to preserve the specimens in their herbaria from the aggressions of insects.
The Rev. J. Wood, writes:[34] “I know to my cost sundry Kaffir articles being absolutely riddled with the burrows of these tiny beetles (Anobium striatum), and not to be handled without pouring out a shower of yellow dust, caused by the ravages of the larva. The most complete wreck which they made was that of a New Guinea bow, which was channelled from end to end by them, and in many places they had left scarcely anything but a very thin shell of wood.
“In such cases I have but one remedy, viz. injecting into the holes spirits of wine in which corrosive sublimate has been dissolved. This is not so tedious a business as it may seem to be, as the spirit will often find its way from one hole to another, so that if half a dozen holes be judiciously selected, the poison will penetrate the whole piece of wood, kill all the insect inhabitants, and render it for ever impervious to their attack. The above-mentioned bow cost me but little trouble. I first shook out the greater part of the yellow powder, and then, placing the bow perpendicularly, injected the spirit into several holes at the upper end. The effect was magical. The little beetles came out of the holes in all directions, and not one survived the touch of the poisoned spirit; many of them, indeed, dying before they could force themselves completely out of the holes. The ticking of the deathwatch is, in fact, the call of the anobium to its mate, and as the insect is always found in old woods, it is very evident why the deathwatch is always heard in old houses. There is, by the way, a species of cockroach which acts in a similar manner, and generally disports itself on board ship, where the sailors know it by the name of ‘Drummer.’”
The earliest account[35] we can find of the use of corrosive sublimate to destroy worms in woods is a few words mentioned, in 1705, by M. Homberg, French Academian. In that year he stated that a person of position in Provence, France, knew how to make a parquet floor which would resist the worm, viz. by soaking the wood in water in which corrosive sublimate had been mixed, and this process he had always found to be very successful.
Herr Temmnick preserved his books from the anobium by dipping them in a solution of quassia. Except on a small scale, however, the saturation of furniture seems scarcely practicable. Fumigation seems, however, to be more available. For small objects, the practice adopted at the Bodleian Library, Oxford, on Professor Westwood’s recommendation, appears good, viz. to enclose a number of volumes in a box, shutting quite close, and placing a small quantity of benzine in a saucer at the bottom of the case. The same plan might be adopted with small ornamental wood-works, enclosing them in glass cases shut as nearly air-tight as possible.
The Report of the Commission appointed by the Department of Science and Art to inquire into the causes of decay in wood carvings, and the means of preventing and remedying the effects of such decay, which was published in 1864, states that the action of the worm in wood carvings may be arrested, and the worm itself destroyed, by vaporization, more especially by the vapour of benzine; and that, after the worm has been destroyed, further attacks from it can be prevented by treating the carved work with a solution of chloride of mercury, either in methylated spirits of wine, or parchment size, according to the surface character of the carving or woodwork; the strength of the solution in each case being 60 grains of the chloride of mercury to a pint of fluid, whether spirits of wine or parchment size. The carving or woodwork should be placed in a box, made as air-tight as possible, but with means of renewing the benzine placed in saucers from time to time as it evaporates without opening the lid of the box. Gilded carved work and panels on which pictures have been painted, and which have been attacked by the worm, can only be treated by applying the fumes of the benzine to the back of the pictures or gilded carved work: there is no reason to suppose that the vapour of the benzine would influence either the gilding of the one or the colours of the other.