300 MEMORANDA. 



■' Before quitting the subject of mounting', I may mention that 

 I have found the common balsam of copaiba a useful medium 

 in which to preserve objects of a delicate character, which it 

 is not desired to mount immediately. I have used it cold, and 

 have mounted the objects in it temporarily between two plates 

 of glass ; and have transmitted them by post and otherwise to 

 distant parts of the country in perfect safety ; objects so pre- 

 pared may at once be mounted in Canada balsam without 

 further preparation. The advantage derived from the use of 

 copaiba is that it is not so viscid, and does not dry so rapidly as 

 the other balsam, while its refracting properties are so little 

 inferior that no detriment results from its use. 



"• The next point on which I have to make an observation that 

 1 believe to be original, is the mode of killing insects and other 

 small animals. A paper recently read to the British Associa- 

 tion mentions that cyanide of potassium has been employed for 

 this purpose. I have had occasion to make some rather large 

 quantities of this salt for other processes, and contemplated the 

 employment of it as a means of destruction, for which its active 

 poisonous property eventually fits it, but I was so well satisfied 

 with other plans, that I have not yet tried it. I find that im- 

 mersion in turpentine kills small insects almost instantaneously, 

 and has the great advantage of making them protrude their 

 probosces, lancets, and other organs — a very desirable effect ; 

 they are also more readily saturated and rendered diaphanous 

 than after they have been allowed to harden. If it is intended 

 to dissect the internal organs this plan wJll not do, and Swam- 

 merdam's plan of suffocating the animals in spirits will be found 

 almost as rapid, and much more suitable. But the agent I most 

 incline to in cases when turpentine is inadmissible, both on the 

 ground of humanity, as causing speedy death, and for its pre- 

 servative quality, which renders it suitable for the cabinet, is 

 creosote. If the mouth and spiracles be touched with a pencil 

 dipped in it, the creatures most tenacious of life soon yield to 

 its influence. The use of spirit to suffocate the animal, and the 

 exhibition of creosote to its mouth, &c., both present the advan- 

 tage of hardening the viscera, which is very desirable, as it 

 tends materially to assist the process of dissection — at least so 

 long as the albuminous portions are not so much coagulated as 

 to make the delicate organs cling together. There is risk, how- 

 ever, that cyanide of potassium would corrode delicate organ- 

 isms, and thus be productive of mischief. Small soft-bodied 

 animals are, by soaking in spirit, rendered less liable to injury 

 in the process of compression. 



" For the purpose of collecting aquatic animalcules, I use, in 

 preference to any kind of net, stout tin hoops, about four inches 



