E 21.1-E 22.1 EMBEDDING MEDIA 647 



21.1 Peeters 1921 6630,85:15 



method: [95% ale] -^ amyl ale. — * amyl ale, fresh portion, 52°C. -^ equal parts 



paraffin and amyl ale. 52°C. — ♦ paraffin 

 note: Larbaud 1921 (6628, 172:1317) uses butyl ale. by the same technique. 



21.1 Pohlman test. 1930 Guyer Guyer 1930, 43 



FORMULA : 52° paraffin 10, bayberry wax 1 



21.1 Ruffini 1927 Ruffini 1927, 28 



formula: paraffin (MP 52°-54°C.) 100, beeswax 10, lard 15 



21.1 Seller 1881 Seller 1881, 48 



formula: paraffin 65, tallow 35 



21.1 Sherman and Smith 1938 591b (tech suppl.), 2:171 



preparation of stock: To 100 paraffin (MP 55°C.) at 78°C. add 12.5 crepe rubber at 



the rate of about 3 every 12 hours; continue heating till homogeneous. 

 WORKING medium: paraffin (MP 55°C.) 100, stock 2.5, beeswax 5 



21.1 Spec 1885 23632, 2 :7 



method: Heat paraffin of 50^0. melting point until it turns yellow. 



21.1 Steedman 1947 17510,88:123 



formula: ethylene glycol monostearate 10, ethylene glycol distearate 73, stearic acid 5, 

 ethyl cellulose 4, castor oil 8 



21.1 Steedman 1949 14900,164:1084 



formula : diethylene glycol distearate 80, ethyl cellulose (low viscosity) 4, stearic acid 5, 



castor oil 4, diethylene glycol monostearate 5 

 note: This composition melts at 53°C. but cuts well at 80''-90°F. 



21.1 van Walsem 1892 22238, 1 :32 



formula: paraffin MP 55°C. 95, beeswax 5 

 recommended for: very large sections. 



21.1 Waterman 1939 20540b, 14:55 



formula: paraffin 80, stearic acid 16, spermaceti 3, bayberry wax 1 

 note: This mixture melts about 3°C. below the melting point of the paraffin base, but it 

 is sufficiently hard to cut good sections at room temperatures. 



22 NITROCELLULOSE MEDIA 



Nitrocellulose is a very loose term covering a large number of mixtures of chemical 

 compounds. These mixtures are usually differentiated according to the viscosity of a 

 standard solution which is tested by timing the rate of fall of a steel ball. A half-second 

 nitrocellulose would, therefore, be of low viscosity and a thirty-second nitrocellulose of 

 very high viscosity. Only the very low viscosity nitrocelluloses are suitable for embed- 

 ding, and the term celloidin (a registered trademark), is now used for any nitrocellulose 

 suitable for the purpose. In the section which follows, are given mostly methods rather 

 than formulas. 



22.1 Formulas 



22.1 Bauer 1941 23632, 58:44 



method: [object, washed free of fixative]—* equal parts pyridine and 4% celloidin, 

 24 hrs. — > 9% celloidin, 24 hrs. — > [make block] 



22.1 Brown 1948 20540b, 23 :83 



reagents required: A. 2% celloidin; B. 4% celloidin; C. 6% celloidin; D. chloroform; 



E. benzene; F. sat. sol. paraffin in benzene; G. paraffin 

 method: [perfectly dehydrated specimens] — » A, 12-24 hrs. — > B, 12-24 hrs. — >• C, 2-4 

 days — ♦ D, vapor, till firm — * E, 6-12 hrs. in each of three changes — » F, 37°C., 1 day 

 — ♦ G, 12-24 hrs. in each of three changes 



