1893.] 107 



But collectors of foreign insects usually use boxes, not fitted with 

 cells. In large collections several hundreds of boxes are necessary, 

 and it is obvious that care must Le exercised. Yet it is wonderful 

 how little care is necessary when, as is usual in collections of foreign 

 insects, long pins are used. Still, the much-dreaded Anthrenus, to say 

 nothing of minor pests, will occasionally appear, and often do incalcu- 

 lable damage before it is detected. And this applies more forcibly to 

 store and duplicate boxes. 



As preservatives, Prof. Riley mentions naphthaline (in the form of 

 "cones" on pins), bisulphide of carbon (an e\il-sme]llng liquid), 

 mercury pellets, and carbolic acid (Dr. Sharp has told us how to apply 

 the latter in our last No.). Mercury has been found objectionable 

 by those who have used it, both in its crude form and as corrosive 

 sublimate. To English readers it will appear strange that he does not 

 even allude to camphor, but he accuses naphthaline of having the same 

 bad properties, viz., the development of " grease," and the precipitation 

 of crystals on the insects. In this respect ray own experience is dis- 

 tinctly in favour of naphthaline, which in the " pure " form ordinarily 

 used here has not been found by me to deposit crystals ; from a 

 chemical point of view, I presume the impure or albo-carbon form 

 should be richer in the preservative elements, but on volatilization it 

 usually leaves an objectionable bitumenous residuum. 



Prof. Eiley makes no mention of arsenic, and it is little in use 

 amongst entomologists. It was brought to my notice many years ago 

 by my now venerable friend, Baron de Selys-Longchamps. The idea 

 originated, however, with the late Mr. H. W. Bates. When the latter 

 was on the Amazons he found that his insects suffered dreadfully from 

 pests, and it occurred to him to make up some of the arsenical soap 

 he used for skins into a semi-liquid condition and to paint the bottoms 

 of his boxes with it. From that time forward the pests ceased to 

 trouble him. Baron de Selys acted on the suggestion, and used 

 arsenic combined (I think) with plaster of Paris as a paint for the 

 insides of his drawers and boxes, and found it infallible, which I 

 can confirm, so far as regards certain cigar boxes adapted as store 

 boxes, so prepared by him, and which I have had for years. For 

 cabinet drawers this " paint " has certain objections ; but arsenic can 

 be used in another form. It must now be quite 15 years ago since 

 my friend gave me two bottles of solution of arsenic in rectified 

 alcohol. In the one case it was the ordinary arsenious acid (the white 

 arsenic of commerce) in the other arsenite of soda. The quantity of 

 arsenic necessary is that enough to cause a just appreciable deposit when 



