CUPRAMMONIA. 15 



To prepare it an aqueous solution of sodic 

 hydrate is slowly added to a solution of cupric sul- 

 phate, until a precipitate of cupric hydrate forms. 

 The precipitate is collected on a filter, transferred 

 to a test tube, washed, and dissolved in strong 

 ammonia. The solution, which is of a beautiful 

 dark-blue color, is at once ready for use. 



It may also be prepared by allowing 16 per cent, 

 ammonia to stand upon copper turnings in an open 

 flask. However prepared, it should be used only 

 so long as it has the power of quickly dissolving 

 cotton fibers. 



Pure cellulose swells much and is dissolved with- 

 out conversion into amyloid. Cell-walls incrusted 

 with lignin, subenn, etc., are only dissolved after 

 these substances have been removed by Schultze's 

 maceration. 



In general, neither the cuticle nor the so-called 

 middle lamella or intercellular substance dis- 

 solves. 



According to Kabsch, cuprammonia is a test for 

 pectose. When a tissue containing this substance 

 is treated with the reagent a fine skeleton of cupric 

 pectate is left behind. 1 



1 Schweitzer: Vierteljahrschrift, nat. Ges., Zurich, 1857, II. Kabsch: 

 Jahrb. wiss. Bot., 1863, p. 357. Hofmeister : Handbuch, I., p. 240. 

 Dippel : Das Mikroskop, I., p. 280. Wiesner : Technische Mikroskopie, 

 1867, p. 38. note 2. Nageli: Das Mikroskop, 1877, p. 474. Fremy: 

 Mem. de 1' Acad., Paris, 1859; Journ. de Pharm. et Chim., XXXVI. Ep- 

 stein : De Conjunctione cellulosse cum cupro oxydato. Dissertatio, Bres- 

 lau, 1860 (Cf, Bot. Zeit, 1860, p. 234). 



