146 



in Fig. I. It consists of a tripod (F) ; a copper plate (A) 

 about fifteen inches long, -five inches wide, and one-eighth 

 to three-sixteenths of an inch thick ; and two tin trays 

 (B) (only one is shown in the diagram); these are ten 

 inches long, two wide, and three deep. They are partly 

 filled with paraffin ; the one with soft, the other with the 

 hard. If an alcohol lamp or a Bunsen burner be so placed 

 that the end of the flame (G) touches one end of the cop- 

 per plate, as shown in diagram, and the trays containing 

 the hard and soft paraffin be placed on the copper plate 

 toward the end away from the flame, it will be found that 

 after a short time, fifteen to thirty minutes, the paraffin in 

 the end of the trays near the flame will be melted while in 

 the other end it is yet hard, by reason of the fact that the 

 flame end of the copper plate has a higher temperature 

 than the opposite end. With a little patience the trays may 

 be so adjusted, by moving them toward or away from the 

 flame, that about half of the paraffin will be melted, the 

 rest not. As shown in the diagram, D represents the area of 

 melted paraffin, E of the unmelted. It of course stands 

 to reason, that if the two trays be placed side by side on 

 the copper plate, the one containing the hard paraffin needs 

 to be nearer the flame than the one containing the soft, to 

 obtain in each an area of melted and unmelted paraffin. 

 In either tray, the area of unmelted paraffin acts as a ther- 

 mometer, the adjoining melted paraffin must have a tem- 

 perature, which, when expressed in degrees, is about the 

 melting point of the paraffin in question; about 40 C. for 

 the soft, 50 C. for the hard. It is not advisable to allow 

 the tissues to rest on the bottom of the tray. A loop can 

 easily be made with a strip of filter paper about two inches 

 wide ; this is supported from a wire or glass rod, and allowed 

 to hang in the area of melted, near the edge of the 

 unmelted paraffin, C in the figure. The tissues are placed 

 on the filter paper. 



When the tissues are thoroughly permeated with the 

 hard paraffin, a rectangular trough is made with two metalic 

 L's, resting on a glass plate, and filled with melted hard 

 paraffin. Into this the tissue is placed by means of a pair 

 of small forceps, which before using were warmed in a 



