Mr. Schwarz states (_Proc. Ent. Soc. of Washington_, Vol. I, page 63) that in place of these cones a form of naphthaline may be used which is known in commerce as "white carbon," and is put up in the form of small square rods for use in intensifying the flames of gaslight. The material is very cheap, costing only 8 cents per pound wholesale, and may be broken up into small pieces, wrapped in paper, and pinned. The use of naphthaline cones is not advisable in boxes containing delicate specimens, as it leaves a deposit which dulls the colors and encourages greasing. The deliquescence of the naphthaline cones produces a blackish, oily residuum which will soil the lining of the box, and it is always advisable either to pin a piece of blotting paper beneath the cone or to wrap this in paper. Constant watchfulness is necessary to see that the eggs which have been deposited and checked in development by the application of this insecticide do not ultimately hatch and start a new generation in the insect box. _Bisulphide of Carbon._--If the collection is found to be infested with insect pests, it may be renovated by pouring a little bisulphide of carbon into the boxes and closing them at once. This substance evaporates rapidly and will destroy all insect life, and does not injure specimens or pins nor stain the boxes. If infested specimens are received, these should be inclosed in a tight box and treated with bisulphide of carbon before being added to the general collection, and it is always well for those who are receiving pinned specimens by exchange or otherwise to keep a quarantine box of this kind on hand. _Mercury Pellets._--The use of mercury pellets is recommended to free boxes from Mites, Psoci, etc., and also to collect any particles of dust which may gain entrance. A few small pellets of mercury, placed free in the bottom of the horizontal box will, by the movement of the box, be caused to roll to and fro and accomplish the desired end. _Carbolic Acid._--Mr. A. T. Marshall (_Entomologist's Monthly Magazine_, Dec., 1873, p. 176) records that he washes the paper of his boxes with the common disinfecting solution of carbolic acid in two-thirds water, which dries without staining and protects the specimens from Psoci.