BRIEFER ARTICLES 
METHOD OF REPLACING PARAFFIN SOLVENT 
ITH PARAFFIN 
Some years ago LAND’ proposed a method oft insuring the gradual 
saturation with paraffin of the xylol now almost universally used as the 
clearing medium and paraffin solvent in the paraffin method. He 
suggested the placing of a section of fine wire screening below the level 
of the xylol in the shell vial upon which the paraffin ordinarily grated 
into the vial would be held. Such an arrangement obviates the danger 
of allowing the paraffin fragments to fall to the bottom of the container, 
there to be in contact with the material and to surround it almost at 
once with a high percentage of dissolved paraffin. 
For some years previous to the publication of LAND’s suggestion in 
this matter we had been employing, in this laboratory, similar devices 
to insure the gradual saturation of the paraffin solvent. Some time ago, 
however, we replaced this-‘method for most material with another which 
is more simple and has given consistently good results. In this scheme 
melted paraffin is carefully poured on the surface of the xylol in a shell 
vial until a plug of the desired thickness is formed. A hot needle run 
around the inside of the vial will loosen the plug of paraffin, which is then 
pushed down below the level of the xylol. We have never found an 
instance in which the paraffin plug slipped down to the bottom of the 
vial or indeed changed its original position appreciably. 
The entire paraffin plug becomes rather rapidly saturated with xylol 
and a layer of xylol-paraffin soon forms at the lower surface of contact. 
If the vial is not shaken, a very gradual saturation of the xylol takes 
place, and at the end of 4-6 days the xylol has taken up its maximum 
quantity of paraffin. In practice we pour a plug of paraffin which will 
weigh 4-6 gr. into a vial containing 10-15 cc. of xylol. 
The increase in time required according to this scheme in the paraffin 
method seems justified by the rather ideally slow replacing of the paraffin 
solvent by paraffin. It is often desirable to cool the vial containing the 
*Lanp, W. J. G., Microchemical methods, an improved method of replacing the 
paraffin solvent with ‘pareifin. Bort. GAZ. 59: 397-1915. 
381] [Botanical Gazette, vol. 66 
