214 MICHIGAN ACADEMY OF SCIENCE, 



PREPARATION FOR DISSECTING PANS. 



S. O. MxVST. 



In vieAV of the fact that such pi-eparatious for dissectiiiji pans as are 

 on the market at present, are either expensive or not very serviceable, 

 or both, it was thought worth while to attempt to work up some mixture 

 that would be more serviceable and less expensive. 



An ideal preparation for dissecting pans, it seems to me, should be of 

 such a nature that it will hold the pins. It should be soft enough so 

 as not to crack when bent, adhesive enough to stick to the pans, black 

 enough to form a sharp contrast with delicate tissues, and insoluble in 

 solutions (water, seventy per cent, alcohol, and formal) commonly used 

 in dissection. 



After considerable experimenting, two preparations were obtained, 

 neither of which prove to be ideal. The formulae of these two prepara- 

 tions (A and B) are as follows: 



PREPARATION A. 



25 grams of linseed oil. 



50 grams of coal tar. 



200 grams of brown resin. 



50 grams of hard paraffin. 



PREPARATION B. 



50 grams of coal tar. i 



100 grams of brown resin. 

 250 grams of hard paraffin. 



The ingredients of preparation (A) mix most readily if all but the 

 paraffin is first melted and thoroughly mixed, and then the paraffin added 

 and melted and thoroughly stirred. This preparation may l)e made 

 harder by continuous heating or by decreasing the amount of linseed oil, 

 and softer by increasing the proportion of linseed oil. 



As in preparation (A) so in preparation (B), a more thorough mix- 

 ture is obtained if the coal tar and resin are first well mixed and then 

 the paraffin added, than if all the ingredients are at once melted together. 

 This preparation requires more heating and stirring than preparation 

 (A) in order to cause the ingredients to mix; and at best there will be 

 only a partial mixture. Coal tar and resin being heavier than paraffin 

 tend to collect at the bottom so that in this preparation, it was found 

 best to weigh out the desired amount of substances used, in proper pro- 

 portion for eacli ]»an separately, and melt and mix them in each pan. 



As above stated, neilher of these preparations is ideal; both lack some 

 essential characteristics. Preparation (A) while insoluble in water and 

 formal is slightly soluble in sixty per cent, alcohol, and quite readily 



