290 
SUMMARY OF CURRENT RESEARCHES RELATING TO 
and when well settled filter a number of times, or clarify it as varnish is 
clarified. This would become a rapid drying medium per se. Resins 
might be treated with chromate of lead in the same manner. Whether 
this suggestion is practical I will leave for others to decide who have 
more experience and skill in chemistry than I. 
What can be done with sulphur and phosphorus ? Can we dissolve 
sulphur in oil and make a transparent medium of it ? 
There are phosphorus, 2 • 224 ; carbonate of lead, 1 * 866 ; oil of anise 
seed, 1*111; bisulphide of carbon, 1*678 — all pretty high — what 
can be done with them ? There may be other substances higher and 
better than those mentioned. How many will act in this important 
matter ? ” 
Useful Mounting Menstruum.* — Dr. Alfred C. Stokes writes : — “ In 
a recent number of ‘ Malpighia ’ M. Aser Poli called attention to the oil 
of cajeput as a valuable medium in which to place objects before their 
permanent mounting in Canada balsam, it being used as a clearing 
agent instead of the oil of cloves. He states that it is soluble in dilute 
alcohol, and thus permits of the direct transfer of the object to it, thereby 
avoiding the use of absolute alcohol. He also remarks that trials with 
the oil have been followed by beautiful results, the preparations being 
perfectly clear, and that delicate objects such as the marine Algae, which 
are among the most difficult to preserve in a satisfactory way, are, when 
treated with the oil of cajeput, almost entirely free from the ordinary 
obnoxious shrinkage. 
These qualities are all excellent ones, and by the microscopist that 
does but little work in mounting, the chance to simplify the operation 
should be hailed with joy. To do away with one of the processes that 
modern methods seem to consider necessary will be a boon. By the use 
of the oil of cajeput the worker can simplify his methods by discarding 
the absolute alcohol, and thus not only save himself considerable trouble 
and some time, but some expense, as an object cleared or soaked in 
oil of cloves cannot well be transferred from it to balsam without the 
intervention of absolute alcohol. 
After having been cleared or soaked in the cajeput oil, the object 
may at once be mounted in the ordinary balsam, or in that dissolved in 
benzol or in chloroform. Absolute alcohol must be kept in a specially 
prepared bottle, as it evaporates rapidly and absorbs water greedily. To 
avoid its use is pleasant indeed. 
Since reading M. Poli’s account of the action of the oil I have been 
making a few experiments, and refer to them here in the hope that 
some that in their microscopical work have more need of mounting 
than I, will take the subject, continue the experiments, and report the 
results. 
In my limited experience I have been pleased with the oil. It has 
a pleasantly aromatic odour and pale-green colour that are in no way 
objectionable. 
Placed on a glass slip it evaporates, but not with such haste that the 
microscopist must hurry his movement to do as he would before it is 
gone ; it evaporates somewhat slowly, and leaves no trace on the glass. 
* Microscope, xi. (1891) pp. 4-6. 
