ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
291 
It is soluble in carbolic acid, or the commercial liquid acid as obtained of 
the druggist is soluble in it. With old benzol balsam that had become 
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 experiment. In dilute alcohol it is, as 
M. Poli has said, perfectly 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 result. 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 balsam 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, how- 
ever, 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 balsam ; 
and the simplifying of the process should be greatly in its favour with 
those that are not professional preparers, and are therefore not ready to 
give any amount of time and attention to their special work. 
I have not tried it with staining fluids. This I must leave to others. 
M. Poli, however, in the note already referred to, says that objects treated 
with it, stained green and then mounted in Canada balsam, retain 
their colour. Further than that nothing is known about this part of the 
subject. 
The reader will perceive that my experiments have been few and of 
little importance. I mention the matter only because I believe the 
menstruum will prove to be an exceedingly useful one, especially to the 
amateur, to whom the simplifying of the process and the avoidance of 
the use of absolute alcohol should certainly make it acceptable. The 
suggestion is not original with M. Poli, as the oil has been used by 
others and referred to in print, but has never come into general use as 
it should. 
(6) Miscellaneous. 
Desk for Microscopical Drawing.* — Dr. Giesenhagen has devised 
a desk or framework for microscopical drawing which is very easy 
to manage. The construction of the apparatus is easily understood 
Zeitschr. f. Wiss. Mikr., vii. (1890) pp. 169-72 (2 figs.). 
