l\4r misc. publication 679, u. s. dept. of agriculture 



Supplies 



Description Quantity 



Methyl or ethyl methacrylate monomer (produced by E. I. du Pont 



de Nemours & Co. , Inc. , and by Rohm and Haas Co.) 8 lb. or more. 



Oxidizing catalyst, which may be any of the following, as preferred: 

 Benzoyl peroxide (preferably with 75 percent inert filler, available 

 under trade name Luperco-A), lauroyl peroxide, or tertiary butyl 

 hydroperoxide 2oz. or more . 



Acetone, anhydrous 4 lb. or more. 



Denatured alcohol, 95 percent (95 percent ethyl alcohol preferable) 2 lb. 



Toluene (Toluol) 2 1b. 



Sodium hydroxide, reagent grade, pellets or sticks 1 lb. or more. 



Calcium chloride, anhydrous, granular, porous, 8-mesh 5 lb. or more. 



Gelatin V 2 lb. 



Filter paper, Whatman No. 40 or equivalent, 9 cm. diameter or 



larger 1 pkg. 



Hydrogen-ion indicator papers for pH 7.0 to 9.0 (or indicator solu- 

 tions for same range) 



Cellophane, regular (not moistureproof) 1 roll. 



Tinfoil (medium weight) 5sq.ft.ormore. 



Scotch cellulose tape, z /i inch or 1 inch wide 1 roll. 



Assorted stoppers (cork and rubber) 



Sandpaper (wet-or-dry type) assorted grits, 2/0, 4/0, and 7/0, or 



equivalent 6 sheets of each. 



Tripoli polish, or other available polishing compound suitable for 



acrylic plastics , such as Lucite or Plexiglas 1 stick. 



Window glass, 9 x 12 inches, or larger 12 pieces. 



The equipment and supply items included in the foregoing lists are 

 intended to meet the average requirements for undertaking the embed- 

 ment of biological specimens on a limited scale. The quantities are 

 based on the needs of one or two workers and should therefore be in- 

 creased proportionately where the number of persons engaging in the 

 work is larger. 



Some of the substances listed are poisonous; some are flammable; 

 and some are both. Such hazardous substances should be stored in 

 unbreakable containers, so far as possible, in a locked metal cabinet. 

 Where more than one person is engaged in the operations, the storage 

 and dispensing of hazardous substances should be the responsibility of 

 one person. 



PROPERTIES OF METHYL AND ETHYL METHACRYLATES 



In the monomeric state, the form in which they are produced and 

 supplied for embedding and casting purposes, both methyl methacrylate 

 and ethyl methacrylate are mobile inflammable liquids having low flash 

 points and giving off combustible and somewhat toxic vapors. When 

 subjected to the catalytic action of free oxygen, to heat, or to ultraviolet 

 radiation, these liquids are converted hy polymerization into clear, 

 colorless, plastic solids which are very stable and nonvolatile at all 

 temperatures ordinarily encountered. 



When polymerization of the liquid takes place a shrinkage of approxi- 

 mately 20 percent in volume occurs with corresponding increase in 

 density, and considerable heat is generated as a result of the strongly 

 exothermic character of the reaction. Unless conditions are properly 

 controlled, the heat liberated during polymerization tends to build up 

 high temperatures within the solidifying mass and cause the reaction to 



