174 JOURNAL, BOMBAY NATURAL HISTORY SOCIETY, Vol. XVIII. 



One or two cyanide killing-bottles, not too large to be carried in the pocket 

 when required ; or a larger-sized cyanide killing-jar, or materials for making 

 same, as follows : | lb. of cyanide of potassium/ 5 1 lb. of plaster of Paris, a 

 glass jar with wide mouth and closely fitting lid.f 



ble get them cut by a book-binder's machine. Paint the box over with liquid glue, and 

 wrap the jaconet round it : it is particularly important lhat the edges of the glass and lid 

 should be well protected ; and it will be found that by gently pulling the jaconet it will 

 wrap itsslf r und the*e without difficulty. Wh^n quite dry, say the following day, the box 

 should be given a coat of Aspinall's enamel, or of paint, a second (and if necessary a third) 

 coat of pa ; nt being added after the first is dry. Any paint or glue on the glass can be re- 

 rnoveH with a p=nkn fe; if the jaconet protrudes too fa r over the ylass, cut it round with a 

 penknife and remove it. (Glass-bottomed boxes alrtady protected in this manner can be 

 obtained from Miss E. M. Bowdler Sharpe, 4, Barrowgate Road, Chiswick, London, W.) 



A simpler method of protecting the boxes is to coat (hern (especially the joints) with 

 shellac dissolved in :ib-oluie alcohol, 



Glass bottomed boxes of this ki->d constructed of tin are sometimes sold; but these are 

 not to be recommended, since when in use in warm climates they are apt to become very 

 hot, with the result that flies contained in them are killed and become dry prematurely. 



*If it is intended to take cyanide to a damp tropical climate, it should be conveyed in the 

 form of lumps, in a bottle with a tightly fitting glass stopper. Cyanide of potassium is also 

 sold in rods, and, in this form, might be conveniently carried in short lengths in herme- 

 tically sealed tubes of thin glass, of diameter and length just sufficient to take the section of 

 cyanide rod. 



t Cyanide killing -bottles can be procured ready for use from Hinton & Co., Bedford Street, 

 Lon ion, W.C, or any other chemist will prepare on? to order; but when Diptera are collected 

 in the manner advised below, it is preferable to use a large-sized killi»g-jar, which should be 

 made as follows : — Take any fairly large glass jar (such as a pickle-bottle) with a wide 

 mouth and closely fitting lid (a lever-lid such as those often fitted to pickle-bottles would 

 answer admirably), and cjver the bot'ora with a layer of dry plaster of Paris to the depth of 

 ^inch; pour in above this a layer equal in depth consisting of powdered cyanide of potas- 

 sium, mixed with rather mnre than its bulk of dry piaster of Paris ; cover this mixture with 

 a layer of dry plaster of Pans to the depth < f J inch or so ; and pour in above the whole a 

 layer £ inch in depth, consisting of plaster of Parts mixed with water to the consistency of 

 cream. As soon as the top layer of plaster is dry the jar is ready for use : the plaster, 

 however, should be covered with several thicknesses of blotting-paper, to avoid risk of 

 injury to specimens in case the surface should at any t me become wet. To obviate tho 

 danger of cracking the jar owing to the heat evolved when plaster of Paris is mixed with 

 water, it may be advisable to stand the jar in warm water before add ng the final layer. 

 The exact amount of cyanide of potassium to be used is of no great consequence ; but in 

 the case of a pronerly prepared jar the odour should be readily perceptible on removing the 

 lid ; if it is not, the reason may be that the mixture is too dry, when a little water poured 

 on to the top layer will probably set matters right. After some months' use the cyanide 

 loses its efficacy (to obviate this so far as possible the jar should never be allowed to remain 

 open), and the mixture must then be renewed. 



A rough-and-ready method of making a Jcilling-jar or bottle is to cover the bottom with a 

 layer of powdered cyanide, and to place above this a number of layers of blotting-paper. 

 The layers of Hotting piper immediately in contact with the cyanide mast be slightly 

 damped; but only sufficient water should be used to cause the cyanide to give off its odour. 

 The top layer of blottiug-paper must on no account be wet, and the less water used the better- 



