666 METHODS AND FORMULAS V 32.1-V 41.1 



32.1 Thiersch test. 1871 Robin Robin 1871, 36 



formula: water 140, gelatin 60, potassium dichromate 7.5, lead nitrate 10 

 preparation: Dissolve 30 gelatin in 70 water with potassium dichromate. Cool to 30°C. 

 Dissolve 30 gelatin in 70 water with lead nitrate. Cool to 30°C. Mix slowly and with 

 constant agitation into dichromate solution. Raise, while constantly stirring, to 

 100°C. Strain. 



32.1 Thiersch test. 1877 Fray Frey, 1877, 113 



formula: stock I sat. aq. sol. {circ. 16%) ferrous sulfate; stock II sat. aq. sol. (circ. 

 33%) potassium ferrocyanide; stock III sat. aq. sol. {circ. 10%) oxalic acid; stock IV 

 gelatin, soaked, strained, and melted 

 WORKING injection mass: Mix stock I 6 and stock IV 15 at about 60°C. Cool to 30°C. 

 Mix stock II 12, stock IV 30. stock III 12 at about 60°C. in order given. Cool to 

 30°C. Add previous mixture to this slowly and continuously with constant stirring. 

 Without ceasing to stir, raise temperature slowly to 100°C. Strain for use. 

 note: This really excellent blue injection mass fell into disrepute through Robin's un- 

 fortunate mistranslation (Robin 1871, p. 35) of Thiersch's original directions. Thiersch 

 took "eine halt gesalligte Losung von schwefelsaurem Eisenoxydul," which was rendered 

 by Robin as "une solution froide satur^e de protoxyde de fer." The wide circulation by 

 Robin of these very obviously impossible directions led to the dropping of the method 

 from the literature. 



32.1 Thiersch (est. 1877 Frey Frey 1877, 115 



formula: water 22, gelatin 40, potassium chromate 1, lead nitrate 5 

 preparation: Dissolve potassium chromate in 12 water. Soak 20 gelatin in water. Drain. 

 Melt and incorporate with chromate solution. Keep at 35°C. Dissolve lead nitrate in 

 10 water. Soak 20 gelatin in water. Drain. Molt and incorporate at 35°C. with lead 

 solution. Then add to lead gelatin mixture at 35°C. slowly and with constant stirring. 

 Raise to 100°C., stirring at intervals for 1-2 hours. Strain. 



32.1 Woodhead test. Cole 1884 Cole 1884b, 29 



formula: water 100, gelatin 10, carmine 4, ammonia 8, acetic acid q.s. 

 preparation: Dissolve carmine in ammonia. Soak gelatin in water. Melt at 40°C. Add 

 to carmine. Add acetic acid to mixture, drop by drop, until color changes. 



V 40 Cleaning Methods and Formulas 



In addition to the five standard methods given below, many people clean slides by 

 flaming them with a bunsen burner. It is difficult to find a satisfactory cloth with which 

 to dry slides after they have been washed, and unless a piece of old linen is available it 

 is usually bettei' to rinse in alcohol and air dry. It was at one time customary to store all 

 clean slides and covers in 95% alcohol, which was alleged to prevent deterioration of the 

 surface. 



There is no known method of removing surface cloudiness from an old slide made of 

 bad quality glass. 



41.1 Methods and Formulas 



41.1 acid alcohol — ronipl. script. 



metuod: dip slides in acid alcohol and dry without rinsing. Masson 1929 (4341), 12:81) 

 recommends 10%, nitric acid in 95% ale; Gray (1952, 113) prefers 1% acetic acid in 

 70% ale. 



41.1 Lysol 



method: heat Lysol lo :il)()ut 150°C. Dip slide and rinse off in water. 

 note: This method will even remove resin, laccjuers, varnishes, and parafFm. 



41.1 scouring powder 



method: make a thin cream of any kitchen scouring powder and water. Dip slides, air 

 dry, and repack in boxes. Polish with cloth before use. 



41.1 sulfuric-dichromate conipl. script. 



formula: to 40 sat. a(|. sol. potassium dichromate add, witli due precautions, 60 sulfuric 

 acid 



