PROCESS OF IMBEDDING IN PARAFFIN 261. 



a good plan to have two bottles of absolute alcohol in each of 

 which the material remains for two hours before it is transferred 

 to the solvent of paraffin or celloidin. 



The Process of Imbedding in Paraffin. — Transfer the 

 material from the absolute alcohol to a phial containing equal 

 parts of absolute alcohol and chloroform, and after two hours 

 place it in a phial of pure chloroform, and again after two hours 

 transfer it to another phial of chloroform, and in these instances 

 enough chloroform to keep the material submerged is all that 

 is needed. Chloroform is a solvent of paraf&n and the ob- 

 ject now is to infiltrate the material with paraffin very gradually. 

 Accordingly after two hours put a small shaving of paraffin 

 into the last phial of chloroform where the material is, 

 and shortly after this has dissolved add another shaving, and 

 so on until the chloroform is saturated with paraffin at the 

 temperature of the laboratory. All this while the material 

 may have been left in the little bag of cheese-cloth for conveni- 

 ence in handling, but now it should be taken out of the bag 

 and laid back loose in the phial of dissolved paraffin. Place 

 this phial on the top of a paraffin oven heated to the melting 

 point of the paraffin, which should be about 52" C. Remove 

 the cork from the phial and let the chloroform evaporate. Add 

 more paraffin a little at a time if needed to keep the ma- 

 terial submerged. Keep the phial on the paraffin oven 

 until the paraffin no longer has a sweetish taste, indicat- 

 ing that all of the chloroform has evaporated. Make a small 

 paper tray by turning up the edges of a piece of paper all around 

 to the height of a centimeter and half fill this with melted 

 paraffin heated hardly above its melting point, and into 

 this pour the contents of the phial — paraffin and material. It 

 is best to have the paper tray on something cold so that a crust 

 of solid paraffin will quickly form at the bottom, and then with 

 heated dissecting needles the material can be disposed in or- 

 derly fashion over this crust, and when the paraffin has entirely 

 hardened each piece of the material can be cut out with a good 

 border of paraffin all around it. When the material has been 



