28 Transactions of the Society. 



I find it useful for other purposes to have at hand in the 

 laboratory a means of producing a vacuum, and it is simple to 

 arrange that the tubing from the aspirator may be fitted whenever 

 desired to another bell-jar with the requisite rubber washer and 

 base, apart altogether from the bath. One can get very rapid and 

 very perfect removal in vacuo of the absolute alcohol by the 

 clearing agent, e.g. xylol or cedar oil. One can also extract 

 absolute alcohol from these substances so that they can be used 

 over again even for the final stages of clearing. 



Then on the bath, paraffin already used, and now no longer free 

 enough from traces of the clearing agent to allow it to be used again 

 for the final embedding, may be rendered fairly pure if kept melted 

 for a time under the aspirator. Even though the actual embedding 

 of objects in paraffin is allowed to proceed in the ordinary way, it 

 is still of very great advantage at the end of the process to submit 

 the dish of melted paraffin, containing the object, for a short time 

 to the action of a vacuum, as in this way the mass, when cooled, 

 will be of uniform consistence and free from crystallization. 



