132 D. E. GODDARD ON MANIPULATION WITH CANADA BALSAM. 



form), that made by Messrs. Duncan, Hockhart, and Co., of Edin- 

 burgh, will be found excellently adapted for the purpose. 



3. — The same precautions should be taken as when using ordinary 

 balsam, such as thoroughly drying the specimen, freeing it from all 

 fatty matter, and submitting it to the action of the air pump. 



4. — Heat may be applied with advantage, but it must be with 

 great caution. As far as I can ascertain, it should not exceed 64 

 cent. (147 Fah.) On cooling, all bubbles disappear, if not at once, 

 in the course of a few days. The balsam hardens immediately on 

 cooling, when it has been subjected to a gentle heat, and is not 

 rendered brittle. Some specimens, such as sections of sponge, &c, 

 should always be allowed to dry or harden gradually, without any 

 application of heat. 



5. — Finally, I consider chloroform and balsam an invaluable 

 addition to the laboratory of the microscopist, and capable of being 

 used with advantage in many cases in which ordinary balsams 

 would prove tedious and troublesome. 



The effect produced by using this medium is to impart a greater 

 brilliancy to objects mounted in it. 



I have endeavoured in this paper to trace the various operations 

 connected with manipulation with Canada balsam. Some of my 

 conclusions may be erroneous — I do not dogmatically lay down 

 principles. I trust that others will either verify my deductions or 

 prove their fallacy by experiment. I shall be most happy to re- 

 consider any part of this paper, and modify any of my statements, 

 provided I can do so on data furnished by the researches of others ; 

 in this age of progress, no department of science can stand still. 

 Perhaps others, with greater experience and more complete experi- 

 ments, will be able to contribute far more valuable material to our 

 common fund of knowledge. I only give certain deductions drawn 

 from the result of my own experiments, and if anything contained 

 in this paper is of the slightest use to any student of microscopical 

 science, or if it induces others to investigate for themselves, I shall 

 not regret having volunteered this paper. 



