The Microscope. 5 



of mounting than I, will take up tlie subject, continue the ex- 

 periments and report the results. 



In my limited experience I have been pleased with the oiL 

 It has a pleasantly aromatic odor, and a pale green color that ig 

 in no way objectionable. Placed on a glass slip it evaporates, 

 but not with such haste that the microscopist must hurry his 

 movements to do as he would, before it is gone ; it evaporates 

 somewhat slowly and leaves no trace on the glass. It is soluble 

 in carbolic acid, or the commercial liquid acid as obtained of the 

 druggist, is soluble in it. Witli old benzol balsam that had be* 

 come so hard and so nearly dry in the bottle that it had to be dug 

 out with a knife in a stringy mass, the oil mixed perfectly, making 

 the old material fluid and easily worked. What its action 

 would be with benzol itself I can only infer from this experi- 

 ment. In dilute alcohol it is, as Monsieur Poll has said, per- 

 fectly soluble. 



After evaporating Canada balsam to glassy hardness in the 

 ordinary way before dissolving it in benzol or in chloroform, I 

 dissolved it in the oil of cajeput, to learn what would be the re 

 suit. This I found to be excellent. The hard balsam dissolves 

 readily in the oil, and makes as thick or as thin a fluid as may 

 be wanted. The solution, however, although readily effected, 

 appears to take place with rather less facility than with benzol 

 or chloroform. Still, it is accomplished by leaving the mixture 

 to itself, the solution being made without attention on the part 

 of the microscopist. 



The results of mounting in the cajeput balsam justify all the 

 good words that M. Poli has spoken of the oil as a clearing 

 medium. After the object has been soaked in dilute alcohol for 

 a convenient time, it is transferred to the oil of cajeput for as 

 long as the microscopist may wish, and thence to the cajeput bah 

 sam in which it is to be mounted. Under the cover glass drying 

 seems to be as rapid as with benzol balsam ; the little that is 

 unavoidably spread on the slip appears, however, to harden 

 rather more slowly, yet I have made no comparative test. The 

 effects of the mounting medium are excellent; as far as I can 

 perceive, quite as good as those from benzol or chloroform bal- 

 sam ; and the simplifying of the process should be greatly in its 

 favor with those that are not professional preparers and are 

 therefore not ready to give any amount of time and attention to 

 their special work. 



