148 Dr. Kane on the Composition of certain Essential Oils. 



chloride of zinc, but I never obtained a result on which I could with satisfaction 

 rely. The residual oil was evidently altered in its nature and appearance, and 

 there always remained in the globe a certain quantity of permanent gas. I 

 attribute the imperfect success of these attempts, to the mutual action of the oil 

 and air of the globe at the high temperature necessary for the experiment ; but 

 by a modification of the apparatus I may possibly at a future period succeed. 



A circumstance connected with the purification of the oils employed in the 

 analyses detailed in this paper requires some notice here, as it has not been ad- 

 verted to under the special heads ; namely, the means used to secure the perfect 

 freedom of the oils from water. This is the more important, as particularly In the 

 results obtained with the oils of marjoram and spearmint, the small quantity of 

 oxygen might be conceived as being derivable from this source, unless proper 

 precaution had been taken. The oils, previous to rectification, were in all cases 

 digested for several days on recently fused chloride of calcium ; then poured off, 

 and distilled ; and the portions selected for analysis allowed to remain In contact 

 for about twelve hours with a few pure fragments of chloride of calcium, before 

 being used. In no case did the oil appear to act on, or dissolve any of the fused 

 salt ; and hence it was only necessary to pour the oil off from the chloride, and 

 not to again distil it, in order to obtain it pure. 



